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72 results on '"Stéphane Scaillet"'

1. Pulsatory volcanism in the Main Ethiopian Rift and its environmental consequences

Author: Zara Franceschini, Raffaello Cioni, Stéphane Scaillet, Gaëlle Prouteau, Giacomo Corti, Federico Sani, Alessandro Mondanaro, Diletta Frascerra, Abate A. Melaku, Bruno Scaillet, Clive Oppenheimer, and Florian Duval
Subjects: Geology, QE1-996.5, Environmental sciences, GE1-350
Abstract: Abstract The East African Rift is one of Earth’s largest continental landforms. It is recognized as a critical region for understanding hominin evolution yet has also undergone important transformation through ongoing tectonic and volcanic activity. An understanding of the interplay of rift kinematics, magma genesis and geomorphic evolution requires firm geochronology but this has been lacking for much of the East African Rift. Here we present detailed stratigraphic observations and high-precision 40Ar/39Ar ages for major volcanic units in the Central Main Ethiopian Rift. Our new data identify a volumetrically major episode of explosive volcanism between circa 3.85–3.42 million years ago, after aproximately 5-million years-long quiescence. Four other pulses followed but with intensity and magnitude declining over time. We suggest that the observed temporal clustering and the pulsatory volcanic activity may have influenced environmental conditions in the area, with possible implications for hominin evolution.
Published: 2024
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2. Hydroclimate variability in the central Mediterranean during MIS 17 interglacial (Middle Pleistocene) highlights timing offset with monsoon activity

Author: Luca Capraro, Alessandro Incarbona, Eliana Fornaciari, Nadia Sabatino, Stéphane Scaillet, Rodolfo Sprovieri, and Mario Sprovieri
Subjects: Medicine, Science
Abstract: Abstract Mediterranean climates are characterized by warm, dry summers and mild, rainy winters. Previous studies suggest that over the last 1.36 Myr, Mediterranean winter rainfalls were in phase with the African monsoon. Here we present a high-resolution terrestrial and marine dataset for the Marine Isotope Stage 17 interglacial (Middle Pleistocene) from Southern Italy, showing that precipitation rates and regimes in the central Mediterranean varied independently of the monsoon system. Specifically, events of extreme summer precipitation were promoted by increased regional insolation rates and/or extratropical cyclones, and their magnitude was further enhanced by the advection of cool and humid North Atlantic air during stadials. Our findings provide new information on the short- to mid-term natural hydroclimatic variability of the Mediterranean basin, and offer new critical insights on land–ocean interactions at the regional scale by complementing previous analyses on the displacement of storm tracks toward southern Europe.
Published: 2023
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3. Aborted propagation of the Ethiopian rift caused by linkage with the Kenyan rift

Author: Giacomo Corti, Raffaello Cioni, Zara Franceschini, Federico Sani, Stéphane Scaillet, Paola Molin, Ilaria Isola, Francesco Mazzarini, Sascha Brune, Derek Keir, Asfaw Erbello, Ameha Muluneh, Finnigan Illsley-Kemp, and Anne Glerum
Subjects: Science
Abstract: Continuous continental rift zones evolve from enigmatic interactions between individual propagating rift segments. Here, the authors document progressive focusing of tectonic and magmatic activity caused by interactions between the Kenyan and Ethiopian rift segments of the East African Rift.
Published: 2019
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4. Defect-controlled Ar40 diffusion-domain structure of white micas from high-resolution Ar40/Ar39 crystal-mapping in slowly-cooled muscovite

Author: Jehiel Nteme, Stéphane Scaillet, Emmanuel Gardés, Florian Duval, Peter Nabelek, and Angelo Mottolese
Subjects: Geochemistry and Petrology
Published: 2023
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5. Atomistic simulations of 40Ar diffusion in muscovite

Author: Jehiel Nteme, Stéphane Scaillet, Pascal Brault, and Laurent Tassan-Got
Subjects: Geochemistry and Petrology
Published: 2022
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6. Sequential development of shear zones in a Metamorphic Core Complex: cause and consequences in the Menderes Massif (Western Turkey)

Author: Vincent Roche, Laurent Jolivet, Stéphane Scaillet, Johann Tuduri, Vincent Bouchot, Laurent Guillou-Frottier, and Erdin Bozkurt
Abstract: During the Cenozoic, the Menderes Massif (western Turkey) records several tectonic and thermal events from subduction to collision, then back-arc extension. But the detailed timing of the succession of different P-T regimes and deformation until today remains debated. To address this, we targeted the main shear zones, providing for the first time a full picture of the 40Ar/39Ar system across the massif. This approach is combined with Tmax, and P-T estimates tied to kinematic-structural data. Extensive sampling along the large top-S Selimiye shear zone allows constraining the deformation at least between 44 and 33 Ma. This shear zone acted as a thrust and was active under HT-MP (530 - 590 °C and 8.5 - 10 kbar). Conversely, the top-S South Menderes Detachment System is associated with a younging of 40Ar/39Ar ages related to exhumation and strain localization during the Late Oligo-Miocene in the Central Menderes Massif. The Bozdağ top-S shear zone then allowed the exhumation of the Bayındır nappe at ~ 21 Ma from high-temperature metamorphic conditions (590 °C). Based on these new elements, we propose for the first time a detailed scenario of the Menderes Massif evolution from the Late Cretaceous to the Present. We finally discuss why the Menderes Massif belongs currently to the regions with the highest geothermal potential in the world. We propose that geothermal activity here is not of magmatic origin but rather associated with active extensional tectonics (detachments) related to the Aegean slab dynamics (i.e., slab retreat and tearing).
Published: 2023
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7. Cenozoic Kinematics of the Wenchuan-Maoxian Fault Implies Crustal Stacking Rather than Channel Flow at the Tibetan Plateau Eastern Margin (Longmen Shan)

Author: Chenglong GE, Philippe Hervé Leloup, Yong Zheng, Stéphane Scaillet, Laura Airaghi, Florian Duval, Jinjiang Zhang, and Haibing Li
Published: 2023
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8. Cenozoic kinematics of the Wenchuan-Maoxian fault implies crustal stacking rather than channel flow extrusion at the eastern margin of Tibetan plateau (Longmen Shan)

Author: Chenglong Ge, Philippe Hervé Leloup, Yong Zheng, Stéphane Scaillet, Laura Airaghi, Florian Duval, Jinjiang Zhang, and Haibing Li
Subjects: Geophysics, Earth-Surface Processes
Published: 2023
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9. Tectonometamorphic and geochronological evolution of the metasediments of the Erzgebirge orogenic wedge (Saxothuringian Domain, Bohemian Massif)

Author: Marine Jouvent, Ondrej Lexa, Vít Peřestý, Petr Jeřábek, Stéphane Scaillet, and Andrew Kylander-Clark
Abstract: Although they provide an important link between deep subduction and mid-crustal processes in the Saxothuringian Domain (Bohemian Massif), the medium to low-grade metasediments surrounding the well-documented (U)HP rocks of the Erzgebirge crystalline complex are scarcely studied. To constrain the Variscan evolution, the transition from the low-grade phyllites to the footwall medium-grade micaschists was investigated. Detailed geochronological (monazite U–Pb and mica 40Ar–39Ar dating), structural and petrological investigations, accompanied by thermodynamic modelling, were performed. We constrained the P–T conditions and timing of four deformation events (D1–D4) identified by structural analysis.The first M1-D1 event is characterized by HP–LT minerals (garnet, chloritoid, phengite, paragonite, and rutile) defining the S1 foliation. The calculated peak P–T conditions for M1 increase from 13 kbar and 520°C in phyllites to 25 kbar and 560°C in micaschists, suggesting a geothermal gradient of 6–11°C/km, typical for subduction environments. The M2-D2 event corresponds to the deformation and metamorphic overprint of the previous fabric during partial decompression. The M3-D3 event is mainly developed in micaschists and intensifies towards the footwall. It is accompanied by a subhorizontal S3 cleavage characterized by MP–MT assemblage bearing biotite, staurolite and ilmenite. The inferred peak P–T conditions for M3 are 5–9 kbar and 595°C representing a barrovian-type geothermal gradient from 17–30°C/km. Finally, all metamorphic fabrics were heterogeneously affected by the low-grade M4-D4 upright folding.Nine samples have been analyzed by in-situ monazite LASS ICP-MS geochronology. In phyllites, there is a prominent single group of ages around 350–340 Ma. In micaschists with intense M3 metamorphism, there are two groups of ages. The monazites located in the M3 matrix were dated at 330 Ma, while few grains in the garnet cores and within locally preserved M1 assemblages are older, around ~340 Ma. 40Ar–39Ar geochronology on micas was used to date 16 samples using step-heating and in-situ UV-laser ablation. The results are consistent with the monazite dating. The phyllites preserve ages spreading between 343–328 Ma, while in micaschists the ages cluster to ~330 Ma. The geochronological data revealed that at least part of the phyllites experienced burial and exhumation between 350–340 Ma, while the burial phase of micaschists is slightly younger (340–335 Ma). The strong M3 metamorphic overprint is restricted to micaschists and is dated around 330 Ma and interpreted as the exhumation, ductile thinning and final cooling of the wedge.The D1-D2 events (350–335 Ma) are interpreted to record the growth and evolution of the Saxothuringian orogenic wedge while its present-day architecture resulted from significant vertical shortening D3 associated with barrovian type metamorphism M3 (330 Ma) and ductile thinning. Altogether, a new tectonic model is proposed, in which the Erzgebirge part of the Saxothuringian Domain reveals a spectacular example of active margin evolution from the formation of accretionary prism to the building of the orogenic wedge by accretion of subducted continental crust and finally its extensional collapse.
Published: 2022
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10. 40 Ar/ 39 Ar Age Constraints on H P /L T Metamorphism in Extensively Overprinted Units: The Example of the Alpujárride Subduction Complex (Betic Cordillera, Spain)

Author: Eloïse Bessière, Stéphane Scaillet, Romain Augier, Laurent Jolivet, Jose Miguel Azañón, Guillermo Booth‐Rea, Adrien Romagny, and Florian Duval
Subjects: Geophysics, Geochemistry and Petrology
Published: 2022
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11. Volcanological evolution of Pantelleria Island (Strait of Sicily) peralkaline volcano: a review

Author: Nina J. Jordan, Silvio G. Rotolo, John C. White, Stéphane Scaillet, Rebecca Williams, Fabio Speranza, Università degli studi di Palermo - University of Palermo, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Eastern Kentucky University, University of Hull [United Kingdom], University of Leicester, Région Centre project ARGON, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011), Silvio G. Rotolo, Stéphane Scaillet, Fabio Speranza, John C. White, Rebecca William, and Nina J. Jordan
Subjects: Paleomagnetism, 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Volcanism, Volcanic explosivity index, 010502 geochemistry & geophysics, 01 natural sciences, Peralkaline rock, Petrography, Paleontology, Caldera, Rheomorphism, 0105 earth and related environmental sciences, General Environmental Science, geography, geography.geographical_feature_category, Ignimbrites, Peralkaline volcanism, Settore GEO/07 - Petrologia E Petrografia, 40 Ar/ 39 Ar, Volcano, [SDU]Sciences of the Universe [physics], Period (geology), General Earth and Planetary Sciences, Peralkaline volcanism, Ignimbrites, Paleomagnetism, 40Ar/39Ar, Rheomorphism, Geology
Abstract: International audience; Pantelleria volcano has a particularly intriguing evolutionary history intimately related to the peralkaline composition of its explosively erupted magmas. Due to the stratigraphic complexity, studies over the last two decades have explored either only the pre-Green Tuff ignimbrite volcanism or the post-Green Tuff activity. We here focus on the whole evolutionary history, detailing the achievements since the first pioneering studies, in order to illustrate how the adoption and integration of progressively more accurate methods (40 Ar/ 39 Ar, paleomagnetism, petrography, and detailed field study) have provided many important independent answers to unresolved questions. We also discuss rheomorphism, a distinct feature at Pantelleria, at various scales and possible evidence for multiple, now hidden, caldera collapses. Although the evolutionary history of Pantelleria has shown that each ignimbrite event was followed by a period of less intense explosivity (as could be the present-day case), new geochronological and geochemical data may indicate a long-term waning of volcanic activity.
Published: 2021
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12. Highly evolved miaskitic syenites deciphering the origin and nature of enriched mantle source of ultrapotassic magmatism in the Variscan orogenic root (Bohemian Massif, Moldanubian Zone)

Author: Martin Kubeš, Jaromír Leichmann, David Buriánek, Markéta Holá, Petr Navrátil, Stéphane Scaillet, and Paul O'Sullivan
Subjects: Geochemistry and Petrology, Geology
Published: 2022
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13. PRESSURE-TEMPERATURE-TIME-DEFORMATION EVOLUTION IN A NON-CYLINDRICAL OROGEN: THE BETIC-RIF CORDILLERA EXAMPLE

Author: Eloïse Bessière, Jacques Précigout, Stéphane Scaillet, José Miguel Azañón, Romain Augier, and Laurent Jolivet
Subjects: Geometry, Deformation (meteorology), Pressure temperature, Geology
Published: 2021
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14. Structural and kinematic evolution of strike-slip shear zones around and in the Central Tianshan: insights for eastward tectonic wedging in the southwest Central Asian Orogenic Belt

Author: Bo Wang, Johan De Grave, Stéphane Scaillet, Xinghua Ni, Jiashuo Liu, Yan Chen, Zhiyuan He, Xin Zhu, State Key Laboratory for Mineral Deposits Research, Nanjing University (NJU), Universiteit Gent = Ghent University [Belgium] (UGENT), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR-10-EQPX-0005,IMAPPI,IRM et TEP couplées en imagerie pré-clinique(2010)
Subjects: Shearing (physics), Tianshan/Tien Shan, geography, Transcurrent tectonics, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Geology, Fault (geology), 010502 geochemistry & geophysics, Strike-slip tectonics, 01 natural sciences, Block rotation, Paleontology, Lineation, Sinistral and dextral, Intracontinental deformation, [SDU]Sciences of the Universe [physics], Oblique convergence and accretion, Late Paleozoic, Shear zone, 0105 earth and related environmental sciences, Mylonite, Zircon
Abstract: International audience; In order to better understand the late Paleozoic tectonic evolution of the southwestern Central Asian Orogenic Belt (CAOB), we carried out structural and geochronological studies on the poorly investigated Xiaergou and Wulasitai shear zones around and in the Chinese Central Tianshan. The Xiaergou shear zone is the connecting segment between the North Tianshan Fault and Main Tianshan Shear Zone along the northern margin of the Yili - Central Tianshan blocks, it strikes NW-SE with a width of ∼3-5 km and shows predominant dextral kinematics. Zircon U-Pb ages of pre- and syn-kinematic granitic dykes within the Xiaergou shear zone indicate that the dextral shearing was active at ∼312-295 Ma. The Wulasitai shear zone is a high-strain belt occurring in the interior of the Central Tianshan block, it extends NW-SE for more than 40 km with variable widths of ∼1-5 km, steep mylonitic foliations and sub-horizontal stretching lineation are well developed and various kinematic indicators suggest prevailing sinistral shearing. New biotite 40Ar/39Ar ages of two meta-sedimentary rocks, together with the published metamorphic zircon ages constrain the timing of the sinistral shearing at ∼312-301 Ma. Our new results combined with the previous studies reveal that the dextral strike-slip shear zones framing the Central Tianshan formed almost simultaneously in the latest Carboniferous (∼310 Ma) and lasted until the middle to late Permian. They resulted from the eastward tectonic wedging and relative rotations between continental blocks in the SW CAOB. The sinistral shearing of the Wulasitai shear zone within the Central Tianshan was likely generated due to differential eastward motions of the northern and southern parts of the Central Tianshan.
Published: 2021
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15. High intensity ignimbritic activity in the Central sector of the Main Ethiopian Rift

Author: Zara Franceschini, Federico Sani, Abate Assen Melaku, Giacomo Corti, Stéphane Scaillet, Raffaello Cioni, Bruno Scaillet, Gaëlle Prouteau, University of Pisa - Università di Pisa, Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Paleontology, Rift, [SDU]Sciences of the Universe [physics], High intensity, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 15. Life on land, Geology, ComputingMilieux_MISCELLANEOUS
Abstract: The volcano-tectonic evolution of the Main Ethiopian Rift (MER) is punctuated with periods of intense silicic volcanism, characterized by large explosive caldera-forming eruptions and the production of several ignimbrite deposits. These volcanic paroxysms require large volume of evolved silicic magma accumulated in shallow chambers into the continental crust; however, the relations between magmatism and tectonics during rifting, and the influence of the distribution and timing of regional tectonics on the ascent of magma and its stalling in large magmatic reservoirs remain poorly defined.We present new geochronological data (40Ar/39Ar dataset of 29 samples) providing new constraints on the timing, evolution and characteristics of volcanism in the Central sector of the MER, where large ignimbrite deposits and remnants of several calderas testify the recurrence of silicic flare-ups. Specifically, we investigate in detail the eastern margin of the rift, where a voluminous, widespread, crystal-rich ignimbrite (Munesa Crystal Tuff, MCT) has been described. This deposit has been correlated to a thick ignimbrite occurring at the bottom of geothermal wells in the rift, pointing to a giant eruptive event attributed to a huge caldera structure, presumably buried beneath the rift floor. At least other two widespread ignimbrite units are present along the same margin for several tens of kilometres, testifying the high volcanicity of this sector of the MER.Our survey and analyses suggest that, at least in the eastern margin of the rift, activity was clustered in periods of large magma production and emission, resulting in the recurrence of intense volcanic phases interspersed with periods of rest of volcanism. Ignimbrites and other volcanic deposits occur in the investigated area, spanning an age interval from 3.5 Ma to as recent as 150 ka. The MCT emission, around 3.5 Ma, was followed, after a long quiescence, by an important phase with the emplacement of both mafic (lava flows and scoria cone) and evolved (ignimbrites) products between 1.9-1.6 Ma. After that, volcanism occurred more frequently, possibly with a lower amount of erupted magma and still alternating with quiescent periods, with volcanism clusters at ~ 1.3-1.2 Ma, ~ 0.8-0.7 Ma and ~ 0.3-0.2 Ma. This clustered volcanic activity will be compared with the episodic rifting of this sector of the Main Ethiopian Rift.
Published: 2020
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16. In Situ and Step-Heating

Author: Alexandre, Beaudoin, Stéphane, Scaillet, Nicolas, Mora, Laurent, Jolivet, and Romain, Augier
Subjects: Geochronology, Tectonics, Tenda massif, shear zone, Regional Crustal Structure, High Strain Deformation Zones, Structural Geology, white mica, 40Ar/39Ar dating, Tectonophysics, Alpine Corsica, Microstructures, in situ and step‐heating combined technics, Radioisotope Geochronology, Planetary Tectonics, Planetary Sciences: Solid Surface Planets, Research Articles, Research Article
Abstract: In order to clarify the link between 40Ar/39Ar record in white mica and deformation, we performed in situ and bulkwise 40Ar/39Ar dating over the East Tenda Shear Zone (Tenda massif, Alpine Corsica). White micas from 11 samples were selected and extensively analyzed using in situ techniques across nested scales of strain‐intensity gradients developed at the expense of a late‐Variscan protolith. 40Ar/39Ar systematics are unaffected by inherited Ar and directly linked to deformation with little or no Ar lattice (volume) diffusion. Extensive sampling allows constraining the end of deformation related to burial and exhumation, respectively, at ~34 and ~22 Ma, bracketing the duration of regional extensional shear to ~12 Myr. Results also highlight a regional strain localization toward the upper contact of the unit with smaller‐scale localization in specific lithologies, notably meta‐aplites. Second‐order complications exist, such as local ill‐defined correlations between ages and finite‐strain microstructures. Thus, the use of a strain gradient as a proxy for strain localization in time is regionally valid but sometimes locally too complex to track or resolve strain partitioning/localization trends at the meter (outcrop) scale and below. Age mixing and incomplete isotopic homogenization by dissolution/precipitation are identified as the main causes of local discrepancies that complicate the link between age and microstructure and the derivation of strain localization rates. Tracking temporal trends in shear distribution across regional‐scale deformation gradients in such settings is possible but requires a multi‐scale approach as implemented here to reveal younging patterns associated to strain localization., Key Points Data are interpretable in terms of age‐deformation relationships and capture a broad‐scale localization of strain in time and spaceAt smaller scale, relating age with structures is more difficult because of greater complexity in 40Ar/39Ar systematicsThe shear zone has a duration of ~12 Myr during exhumation and deformation ended in the upper part of the viscous/brittle transition
Published: 2020

17. Coupling RSCM paleothermometry with 40Ar/39Ar analysis in the south Variscan belt (Cévennes, France): new constraints on the late-orogenic metamorphic gradient in an orogen outer domain

Author: Clément Montmartin, Stéphane Scaillet, Hugues Raimbourg, Michel Faure, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Coupling (electronics), [SDU]Sciences of the Universe [physics], Metamorphic rock, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geophysics, ComputingMilieux_MISCELLANEOUS, Geology, Domain (software engineering)
Abstract: In the SE part of the Variscan French Massif Central, the Cévennes area belongs to the para-autochthonous unit of the southern Variscan belt. This area underwent three metamorphic events (Faure et al., 2001). I) A green schist to low amphibolite facies one (500°C, 4.5Kb Arnaud, 1997) developed in micaschists and quartzites. These rocks were stacked as south-directed nappes during the final stage of the Variscan crustal thickening dated at ca 340 Ma by 40Ar/39Ar on biotite (Caron, 1994). This early event was responsible for the flat-lying foliation, the N-S striking stretching lineation, and intrafolial foliation. II) A high temperature event (680°C, 4.5kb Rakib, 1996) dated at ca 325 Ma (40Ar/39Ar on two biotites, Najoui et al, 2000) overprinted the early one. On the basis of the mineral assemblages of this event, a NE-ward increase of the T conditions was interpreted as a remote effect of the Velay Dome (Rakib, 1996). III) Finally, the Mt-Lozère and Aigoual-St-Guiral-Liron monzogranitic plutons intruded the Cévennes para-autochthonous unit. Monazite and biotite yield U-Pb, and 40Ar/39Ar ages at 315-303Ma and 306 Ma , respectively (Brichaud et al. 2008). The pluton emplacement conditions are determined at 695°C, 1.5Kb (Najoui et al, 2000).We report Raman Spectrometry of Carbonaceous Matter (RSCM) paleotemperature data acquired on more than 100 samples throughout the entire Cévennes area. These show a regional homogeneous thermal distribution with a 535 ± 50 °C mean temperature without any geometric correlation with the nappes structure, nor the granitic intrusions. Moreover, no thermal increase towards the NE can be documented. SW of the Aigoual-St-Guiral-Liron massif, our RSCM data document a temperature jumps between the overlying Cévennes micaschists and the underlying epimetamorphic rocks belonging the the Fold-and-Thust belt unit of the French Massif Central.In order to constrain the age of this regional thermal event, we 40Ar/39Ar dated 25 new regionally-distributed syn- and post-folial muscovites by step heating along two N-S cross sections within the Cévennes micaschists series. In areas distant from the plutons, the muscovite yields a ca 325 Ma age interpreted as the one of the HT event recorded by the RSCM measurements. However, young muscovite ages at ca 305Ma are observed around the plutons. We assume that the heat supplied by the plutons reset these muscovites at around 400°C while the organic matter cannot record the contact metamorphic peak lower than the regional one. Moreover, 40Ar/39Ar in-situ analyses carried out on 5 mm-sized post folial (but deformed) biotites in the central part of the micaschist series provide ages around 320Ma. The presence of a hidden dome, underneath the Cévennes micaschists, similar to the pre-Velay migmatites exposed in the northern part of the Cévennes area (Faure et al., 2001, Be et al., 2006) is discussed.
Published: 2020
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18. Early Permian Paleomagnetic Result from the South Beishan (NW China) and Its Implications for the Tectonic Evolution of the SW Central Asian Orogenic Belt

Author: Xin Zhu, Yan Chen, Michel Faure, Bo Wang, Xinghua Ni, Stéphane Scaillet, State Key Laboratory for Mineral Deposits Research, Nanjing University (NJU), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris
Subjects: Paleomagnetism, Paleontology, Tectonics, Permian, [SDU]Sciences of the Universe [physics], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, China, ComputingMilieux_MISCELLANEOUS, Geology
Abstract: The Beishan Orogenic Belt plays an important role in understanding the Paleozoic tectonic evolution of the Central Asian Orogenic Belt and the final closure time of the Paleo-Asian Ocean. However, although numerous geochronologic, geochemical, and isotopic data have been obtained, no consensus has been reached yet on the Early Permian tectonic setting for this region and, thus, the final closure time of the Paleo-Asian Ocean, mainly because of the nonuniqueness of the interpretations deduced from such data base. Therefore, other methods are urgently needed to provide more constraints from different perspectives. We present here a paleomagnetic study on the Gubaoquan doleritic dike swarm in the South Beishan area. Thermo-magnetic experiments and room-temperature hysteresis loops reveal that single-domain and multi-domain magnetite is the principal carrier of remanence. Anisotropy of magnetic susceptibility of studied dikes shows a horizontal magnetic foliation with a magnetic lineation generally parallel to the dikes’ strike. Plagioclase 40Ar/39Ar dating result of one dolerite sample collected from the margin of a 10m-thick dike provides a cooling age at 300~284 Ma. Scanning electronic microscope observation coupled with energy-dispersive X-ray spectrometry shows that the remanence carrier is mainly euhedral without evident chemical alteration nor secondary mineral formation. Characteristic remanent magnetizations are successfully isolated from twenty dikes, and pass baked contact test. According to Deenen et al. (2011) statistical criteria, the distribution of the remanence directions reflects the contribution from paleosecular variation of the geomagnetic field. Taking all data together, the Gubaoquan doleritic dike swarm probably preserves a primary remanence. Consequently, an Early Permian paleomagnetic pole for the South Beishan can be calculated at λ = 80.2°N, φ = 300.3°E, A95 = 5.3° and N = 20. Comparisons of this new result with published ones from neighboring blocks bring us following implications for the tectonic evolution of the SW CAOB: 1. Neither relative latitudinal movement nor relative rotation can be paleomagnetically detected among Yili, Turpan-Hami, and South Beishan since the Early Permian. 2. Significant relative rotations have taken place between South Junggar and Tarim with respect to South Beishan-Turpan-Hami-Yili, respectively, since the Early Permian, corresponding to large-magnitude strike-slip displacements along mega-shear zones. 3. No obvious relative latitudinal movement has occurred between South Beishan and its neighboring blocks (Tarim, South Junggar, Yili, Turpan-Hami, and Dunhuang) since the Early Permian, combined with other evident, suggesting that the Paleo-Asian Ocean probably have closed before the Early Permian, and South Beishan was in a rift setting in the Early Permian.
Published: 2020
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19. Controls of magma chamber zonation on eruption dynamics and deposits stratigraphy: The case of El Palomar fallout succession (Tenerife, Canary Islands)

Author: María Jiménez-Mejías, Bruno Scaillet, Stéphane Scaillet, Joan Martí, Dario Pedrazzi, Silvia Zafrilla, Domenico M. Doronzo, Joan Andújar, Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Centro Geofísico de Canarias, Instituto Geografico Nacional, Magma - UMR7327, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Martí Molist, Joan [0000-0003-3930-8603], Pedrazzi, Dario [0000-0002-6869-1325], Doronzo, Domenico Maria [0000-0002-6866-8870], Martí Molist, Joan, Pedrazzi, Dario, and Doronzo, Domenico Maria
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, Pyroclastic rock, Magma chamber, Eruption dynamics, Eruption column, 010502 geochemistry & geophysics, 01 natural sciences, Las Cañadas Edifice, Geochemistry and Petrology, El Palomar pumice fall, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, 0105 earth and related environmental sciences, geography, Explosive eruption, geography.geographical_feature_category, Tenerife, Teide, Magma chamber zonation, Geophysics, Volcano, 13. Climate action, Magma, Mafic, Geology
Abstract: Anticipating volcanic eruptions at central volcanoes require knowing how magma chambers prepare for new eruptions. Pre-eruptive processes that occur in such magma chambers are recorded in the products of these eruptions, so their characterisation in terms of magma composition and physics offers the clues to understand past eruptions and predict future ones. Here, we study the very well preserved pyroclastic succession of El Palomar Member (712 ± 41 ka), in Las Cañadas caldera, Teide, Canary Islands. This deposit resulted from a single explosive eruption of a phonolitic magma that started with a sustained eruption column (sub-plinian or plinian) that formed a massive, 40 m thick non-welded fallout deposit, progressively changing into a lower intensity fire fountain that deposited a 25 m thick fallout succession of non-welded to strongly welded pumices. Stratigraphic and petrological data suggest that this eruption was related to a thermally-compositionally zoned and relatively shallow magma chamber in which the arrival of a hotter and more mafic magma rapidly triggered the eruption. The studied deposit shows how this zoned structure was maintained during the whole process, which allows one to reconstruct what happened during the eruption. Comparison of this eruption with the current situation at Teide volcano alerts on the potential rapid preparation for new eruptions in the case that sufficient phonolitic magma was available in the shallow plumbing system of this active volcano if new inputs of deeper magma take place.
Published: 2020
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20. Subduction dynamics beneath the Eastern Mediterranean: tectonic, metamorphic and thermal consequences from Cretaceous to Present

Author: Vincent Roche, Laurent Jolivet, Laurent Guillou-Frottier, Stéphane Scaillet, Vincent Bouchot, Johann Tuduri, Armel Menant, Pietro Sternai, Dimitrios Papanikolaou, Erdin Bozkurt, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), University of Geneva [Switzerland], National and Kapodistrian University of Athens (NKUA), Middle East Technical University [Ankara] (METU), China University of Geosciences [Wuhan] (CUG), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), National and Kapodistrian University of Athens = University of Athens (NKUA | UoA), China University of Geosciences [Wuham] (CUG), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology
Abstract: International audience; Slab dynamics (i.e. rollback and tearing) below the Eastern Mediterranean area is well imaged by numerous mantle tomography studies elucidating deep mantle structures. It induces asthenospheric mantle flow that had first order tectonic and metamorphic consequences in the overriding plate. However, there is no consensus about the time-space evolution, the deformation and the thermal consequences of such dynamics. We combine these information (i.e. mantle tomography) to high-resolution laser 40Ar-39Ar dating of micas, U-Pb dating of monazite, RSCM Tmax data and regional-scale kinematic-structural data in the Menderes Massif and in the Eastern Aegean islands, which have been little studied. This study then shed light on a common regional tectono-metamorphic evolution from Cretaceous to Present. In particular, we demonstrate the existence of different nappes which recorded different high-pressure and low-temperature conditions in the studied area: (i) the Upper Cycladic Blueschist Nappe (exclud-ing the Vourliotes Nappe in Samos) characterized by eclogite paragenese and (ii) the Lower Cycladic Blueschist Nappe (e.g. Amorgos, a part of the Dodecanese and Fourni islands) and the colder units of the upper Menderes Complex (i.e. the Kurudere-Nebiler units) witnessing blueschist metamorphism. A part of these units was partly obliterated by the Eocene Barrovian-type metamorphism overprint associated with collision and crustal stacking events in western Turkey. This event was mainly exhumed along the topS syn-orogenic extensional Selimiye shear zone during the Eocene (47 to 33 Ma, 40Ar/39Ar on micas). Then, a second high-temperature low-pressure meta-morphic event (with local anatexis) associated with post-orogenic extension induced by slab dynamics (i.e. tearing and slab retreat) occurred during the Oligo-Miocene. Our geochronological investigations reveal the formation of a large thermal pulse contemporaneous with the exhumation of the Menderes metamorphic core complex (MCC) and other MCCs in Cyclades. This latter is also exploited for geothermal production today, particularly in the Menderes Massif. In details, we suggest that crustal-scale low-angle normal faults convey hot fluids to the surface and represent the first-order control on geothermal systems. In addition, our study of the Eastern Aegean islands, allows us to complete the description of the extensional strain field in the overriding plate around the Miocene slab tear and retreat. Extensional tectonics keeps a constant NNE-SSW direction, without localized crustal-scale strike-slip faults and block rotations above the tear. Such dynamics are also consistent with numerical modelling, suggesting that, when slab tearing occurs, Moho temperatures can temporarily increase by up to 250 • C due to shear heating controlled by the fast-flow of the uppermost mantle. At the scale of MCCs, the bulk fluid flow pattern is controlled by topography-driven flow while buoyancy-driven flow dominates within the permeable detachments, focusing reservoir location of high-energy geothermal systems at shallow depth beneath detachments.
Published: 2019

21. Diffusion and fluid interaction in Itrongay pegmatite (Madagascar): Evidence from in situ 40Ar/39Ar dating of gem-quality alkali feldspar and U Pb dating of protogenetic apatite inclusions

Author: David Chew, Joshua Davies, Théodore Razakamanana, Stéphane Scaillet, J. Stephen Daly, Daniil Popov, Gary O'Sullivan, Eszter Badenszki, Richard Alan Spikings, Université de Genève = University of Geneva (UNIGE), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Géodynamique - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Trinity College Dublin, Irish Centre for Research in Applied Geosciences (iRAG), University College Dublin [Dublin] (UCD), Université de Toliara, Université du Québec à Montréal = University of Québec in Montréal (UQAM), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011), European Project: 290864,EC:FP7:ERC,ERC-2011-ADG_20110209,RHEOLITH(2012), University of Geneva [Switzerland], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ANR: 10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), and ANR: 11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)
Subjects: 010504 meteorology & atmospheric sciences, Geochronology, Geochemistry, Thermochronology, 010502 geochemistry & geophysics, Feldspar, 01 natural sciences, Itrongay, Diffusion, Madagasca, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Geochemistry and Petrology, ddc:550, r In situ, Apatite, Alkali feldspar, Pegmatite, 0105 earth and related environmental sciences, Radiogenic nuclide, Geology, Crust, U-Pb, 40Ar/39Ar, visual_art, visual_art.visual_art_medium, Fluid interaction, Sedimentary rock, Dating
Abstract: International audience; Alkali feldspar 40Ar/39Ar and apatite UPb geochronological studies have typically invoked two mechanisms to account for apparent loss of radiogenic 40Ar and 206-208Pb. Some studies have suggested that the radiogenic isotopes were lost by volume diffusion and used these dates to constrain temporal variations of rock temperatures; others have argued that the radiogenic isotopes were lost due to interaction with fluids and related these dates to chemical alteration. These two end-member interpretations have fundamentally different implications for tectonic models derived from geochronological data, and therefore it is important to reliably identify the principal mechanism for loss of radiogenic isotopes. Here, we revisit the mechanisms of 40Ar loss in the famous gem-quality alkali feldspar from the Itrongay pegmatite in Madagascar. Previous studies have suggested that volume diffusion is the dominant mechanism of 40Ar loss, providing key evidence to support the use of 40Ar/39Ar dating of alkali feldspar for thermochronology. We attempted to verify these results by obtaining time-temperature paths from petrologically characterised cogenetic feldspar and apatite from the Itrongay pegmatite and comparing them with each other. However, our results suggest that only a minor component in the variability of 40Ar/39Ar dates of Itrongay feldspar is related to the diffusive loss of 40Ar, and that this loss was not compatible with the majority of previously proposed models, which hinders quantitative interpretations. The crystal studied here grew in five episodes related to the influx initially of co-existing dense SiO2-rich solution and CO2-dominated fluid (the first and supposedly the following two episodes) and subsequently of H2O-rich fluid (supposedly the final two episodes). Much greater component in the variability of the acquired 40Ar/39Ar dates is interpreted to reflect the differences in the ages of these growth episodes, which we estimate to span from 477 Ma to 176 Ma (the first four episodes). Apatite inclusions in this crystal are interpreted to be xenocrysts derived from the country rocks of the Itrongay pegmatite. These yield older UPb dates than the estimated age of their host feldspar and have apparently experienced diffusive loss of 206,207Pb prior to entrapment. Our 40Ar/39Ar results indicate that there is a lack of unambiguous evidence for diffusive loss of 40Ar from alkali feldspar that can be readily interpreted for thermochronological purposes. However, in situ 40Ar/39Ar dating of alkali feldspar appears to be a promising tool for tracking fluid-flow events in the Earth's crust whose applicability is not restricted to sedimentary rocks. Our UPb results corroborate previous suggestions that UPb dating of apatite can be used for thermochronology.
Published: 2020
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22. Explosive eruptive history of Pantelleria, Italy: Repeated caldera collapse and ignimbrite emplacement at a peralkaline volcano

Author: Stéphane Scaillet, Fabio Speranza, Silvio G. Rotolo, Nina J. Jordan, Michael J. Branney, Rebecca Williams, William C. McIntosh, Department of Geology [Leicester], University of Leicester, Instituto Nationale di Geofisica e Vulcanologia (INGV), Dipartimento di Scienze della Terra e del Mare [Palermo] (DiSTeM), Università degli studi di Palermo - University of Palermo, School of Environmental Sciences, University of Hull [United Kingdom], Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, New Mexico Bureau of Geology & Mineral Resources, New Mexico Institute of Mining and Technology [New Mexico Tech] (NMT), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), Jordan, N., Rotolo, S., Rebecca, W., Fabio, S., Mcintosh, W., Branney, M., and Stéphane, S.
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, Pyroclastic rock, Trachyte, 010502 geochemistry & geophysics, 01 natural sciences, Peralkaline rock, 40Ar/39Ar dating, Effusive eruption, Geochemistry and Petrology, Pumice, Breccia, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, Eruptive history, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Ignimbrites, Peralkaline volcanism, Settore GEO/07 - Petrologia E Petrografia, Settore GEO/08 - Geochimica E Vulcanologia, Caldera collapse, Peralkaline volcanism Pantelleria Ignimbrites Caldera collapse Eruptive history 40Ar/39Ar dating, Geophysics, Volcano, 13. Climate action, Seismology, Geology, Pantelleria
Abstract: A new, pre-Green Tuff (46 ka) volcanic stratigraphy is presented for the peralkaline Pantelleria Volcano, Italy. New 40Ar/39Ar and paleomagnetic data are combined with detailed field studies to develop a comprehensive stratigraphic reconstruction of the island.We find that the pre-46 ka succession is characterised by eight silicarich peralkaline (trachyte to pantellerite) ignimbrites,many ofwhich blanketed the entire island. The ignimbrites are typically welded to rheomorphic, and are commonly associated with lithic breccias and/or pumice deposits. They record sustained radial pyroclastic density currents fed by lowpyroclastic fountains. The onset of ignimbrite emplacement is typically preceded (more rarely followed) by pumice fallout with limited dispersal, and some eruptions lack any associated pumice fall deposit, suggesting the absence of tall eruption columns. Particular attention is given to the correlation of well-developed lithic breccias in the ignimbrites, interpreted as probable tracers of caldera collapses. They record as many as five caldera collapse events, in contrast to the two events reported to date. Inter-ignimbrite periods are characterised by explosive and effusive eruptions with limited dispersal, such as small pumice cones, as well as pedogenesis. These periods have similar characteristics as the current post-Green Tuff activity on the island, and, while not imminent, it is reasonable to postulate the occurrence of another ignimbrite-forming eruption sometime in the future. © 2017 Elsevier B.V. All rights reserved.
Published: 2018
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23. Deformation behavior of continental crust during subduction and exhumation: Strain distribution over the Tenda massif (Alpine Corsica, France)

Author: Giovanni Luca Cardello, Romain Augier, Alexandre Beaudoin, Hugues Raimbourg, Stéphane Scaillet, Laurent Jolivet, Anthony Jourdon, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Géoazur (GEOAZUR 7329), Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Section des Sciences de la Terre et de l'environnement, Université de Genève (UNIGE), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), European Project: 290864,EC:FP7:ERC,ERC-2011-ADG_20110209,RHEOLITH(2012), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA), ANR-10-LABX-100-01/10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and Université de Genève = University of Geneva (UNIGE)
Subjects: Continental crust, 010504 meteorology & atmospheric sciences, Shear zone, Doming, Tenda massif, Exhumation, 010502 geochemistry & geophysics, 01 natural sciences, Dome (geology), Compression (geology), Petrology, 0105 earth and related environmental sciences, Earth-Surface Processes, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Subduction, Massif, Overprinting, Geophysics, Alpine Corsica, Strain localization, Seismology, Geology
Abstract: International audience; In order to address the question of strain localization within continental units during subduction and exhumation, a large-scale portion of an exhumed continental crust was structurally revisited. The Tenda massif (Alpine Corsica) has recorded burial (D1; top-to-the-SW kinematics) down to blueschist-facies conditions followed by exhumation (D2; top-to-the-NE kinematics). It was so far regarded as a quite rigid unit with strain localization at the upper contact with the overlying oceanic material, the East Tenda Shear Zone (ETSZ), where previous studies were focused. A structural analysis carried out from the core to the boundaries of this continental unit shows instead that deformation is pervasive in the whole section. A reappraisal of the finite structure shows that this unit corresponds to a N140°E elongated dome of D2 fabrics severely overprinting earlier D1 structures, locally preserved in the core of the dome. Field observations show that deformation was distributed at maximum burial, pervasively affecting both the Tenda massif and the overlying tectonically coupled oceanic material. Strain remained distributed during the first steps of exhumation that probably started during the last stages of subduction. After a regional switch from compression to extension, deformation localized toward the ETSZ and other internal shear zones such as the newly described Saleccia Shear Zone, as shown by strain intensity mapping in the eastern granitic protoliths. Doming occurred during this localization when crossing the brittle-ductile transition. This large-scale structural study shows that lithological boundaries controlled the place where strain localized, while the general style of deformation (distributed vs localized) was controlled by depth (i.e. pressure-temperature conditions), interacting with other parameters such as fluid circulation and protolith composition.
Published: 2017
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24. The Early Andean subduction system as an analog to island arcs: Evidence from across-arc geochemical variations in northern Chile

Author: Pablo Rossel, Stéphane Scaillet, Verónica Oliveros, Oscar Figueroa, Leonardo Retamal, Reynaldo Charrier, Mihai N. Ducea, Departamento Ciencias de la Tierra [Concepción], Universidad de Concepción [Chile], Department of Geosciences, University of Arizona, Facultatea de Geologie Geofizica, Universitatea Bucuresti, Escuela Ciencias de la Tierra, Universidad Andrés Bello [Santiago] (UNAB), Departamento de Geología, Universidad de Chile = University of Chile [Santiago] (UCHILE), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Minera Escondida, Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)
Subjects: 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, Andes, Jurassic, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Back-Arc, Volcanism, Extension, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Geochemistry and Petrology, 0105 earth and related environmental sciences, Basalt, geography, geography.geographical_feature_category, Subduction, Volcanic arc, Geology, Crust, 15. Life on land, Volcanic rock, Northern Chile, Magmatism, Island arc
Abstract: International audience; The Upper Jurassic volcanic rocks of the Pre-Cordillera and High Andes of northern Chile (26 - 31°S) represent a back-arc magmatic chain formed during an earlier stage of Andean subduction. After the Callovian, the back-arc basin gradually changed from marine to continental conditions and was characterized by basaltic to rhyolitic rocks erupted along two belts, parallel to the coeval arc. The western belt comprises the Picudo and Algarrobal formations, whereas the eastern belt comprises the Lagunillas Formation and the Quebrada Vicuñita Beds. New major and trace elements data, along with whole rock Sr, Nd and Pb isotopes are presented for these volcanic belts and compared to the geochemical features of the Jurassic and Early Cretaceous arc magmatism. Ar-Ar and U-Pb ages constrain the back arc volcanism to have evolved between 163.9 ± 1.4 and 148.9 ± 1.2 Ma.Rocks belonging to the western belt have steep multi-element patterns and low concentrations of HREE, suggesting the presence of garnet in the source, and a more radiogenic isotopic composition than the arc magmatism. Parental magmas of these back-arc lavas would have been generated through melting of a depleted mantle, although less depleted than the sub-arc mantle, and interacted with minor amounts of Paleozoic crust. The geochemical composition of the rocks belonging to the eastern belt is more heterogeneous and suggests involvement of different magmatic sources, including depleted mantle as well as an OIB-type mantle within the wedge. In spite the fact that the Jurassic Andean arc was built over a continental plate, the architecture of the volcanic chains and geochemical variations observed among the arc and back-arc rocks in northern Chile resemble those in modern island arcs, and thus support the hypothesis that early Andean subduction developed under extensional tectonic conditions.
Published: 2013
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25. Anatomy of the Cycladic Blueschist Unit on Sifnos Island (Cyclades, Greece)

Author: Giovanni Luca Cardello, Stéphane Scaillet, Vincent Roche, Valentin Laurent, Laurent Jolivet, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Géodynamique - UMR7327, Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), European Project: 290864,EC:FP7:ERC,ERC-2011-ADG_20110209,RHEOLITH(2012), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: Blueschist, Accretionary wedge, 010504 meteorology & atmospheric sciences, Subduction, Metamorphic rock, CYCLADES, post-orogenic extension, strain localization, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, syn-orogenic exhumation, 01 natural sciences, Aegean domain, Paleontology, Tectonics, Geophysics, High-pressure and low-temperature metamorphism, 14. Life underwater, Sifnos, Shear zone, Eclogite, Geology, Seismology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: In press, accepted manuscript; International audience; Since 35 Ma, the kinematics of the Aegean domain has been mainly controlled by the southward retreat of the African slab, inducing back-arc extension. The main structures and associated kinematics are well constrained, but the kinematics of deformation before 35 Ma, coeval with the exhumation of blueschists and eclogites of the Cycladic Blueschist Unit, is still poorly understood. The earlier Eocene syn-orogenic evolution is strongly debated and very different geometrical interpretations and kinematic histories have been proposed in the literature. This study focuses on the high-pressure and low-temperature (HP-LT) parageneses spectacularly exposed and well preserved on Sifnos Island. The new field work provides new structural constraints on the tectonic history of HP-LT units generated in the subduction zone during the Eocene. It further shows how lithological heterogeneities localize strain within an accretionary wedge and how the localisation of strain evolves through time during exhumation. We show, through new geological and metamorphic maps, cross-sections and analyses of kinematic indicators, that Sifnos is characterized by shallow-dipping shear zones reactivating weak zones due to competence contrasts or earlier tectonic contacts. Structures and kinematics associated with these shear zones, show a top-to-the-N to −NE ductile deformation. The lower part of the tectonic pile shows a downward gradient of shearing deformation and is actually a thick top-to-the-NE shear zone, which we name the Apollonia Shear Zone. Through time shearing deformation tends to localize downward, leaving the upper part of the subduction complex preserved from late deformation. The present-day shape and topography of the island is largely controlled by late brittle faults reworking the earlier ductile shear zones. Comparing with the nearby island of Syros, we propose a new tectono-metamorphic evolution of the Cycladic Blueschists Unit, which partly explains the different degrees of retrogression observed on the Cycladic Islands.
Published: 2016
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26. Eruptive and structural history of Teide Volcano and rift zones of Tenerife, Canary Islands

Author: E. Rodríguez Badiola, Urbano Fra-Paleo, A. Hansen, Stéphane Scaillet, Juan Carlos Carracedo, Hervé Guillou, Martine Paterne, Raphaël Paris, F. J. Pérez Torrado, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochrononologie Traceurs Archéométrie (GEOTRAC), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Caja Canarias, Comisión Interministerial de Ciencia y Tecnología, CICYT (España), and Centre National de la Recherche Scientifique (France)
Subjects: Nested central volcanoes, Volcanic hazards, 010504 meteorology & atmospheric sciences, Radioisotopic ages, Canary Islands, Volcanic explosivity index, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Volcanic history, Caldera, Teide Volcano, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, geography, Explosive eruption, geography.geographical_feature_category, Rift, Tenerife, Geology, Rift volcanism, Volcano, Intraplate earthquake, Structural history, Rift zone, Seismology
Abstract: GSA Journals Online - GSA Journals Online Access Control.mht, The Teide and Pico Viejo stratocones and the Northwest and Northeast Rifts are products of the latest eruptive phase of the island of Tenerife, initiated with the lateral collapse of its northern flank that formed the Las Cañadas Caldera and the Icod–La Guancha Valley ca. 200 ka. The eruptive and structural evolution of this volcanic complex has been reconstructed after detailed geological mapping and radioisotopic dating of the significant eruptive events. A set of 54 new 14C and K/Ar ages provides precise age control of the recent eruptive history of Tenerife, particularly Teide Volcano, the third-highest volcanic feature on Earth (3718 m above sea level, >7 km high), and unique in terms of its intraplate setting. The development of the Teide–Pico Viejo Volcanoes may be related to the activity of the Northwest and Northeast Rifts. Volcanic and intrusive activity along both rift zones may have played an important role in activating the gravitational landslide and in the subsequent growth, nested within the collapse embayment, of an increasingly higher central volcano with progressively differentiated magmas. The coeval growth of the central volcano with sustained activity along the rifts led to a clear bimodal distribution in composition of eruptive products, with the basaltic eruptions in the distal part of the rifts and phonolitic and more explosive eruptions in the central area, where the differentiated stratocones developed. Current volcanic hazard in Tenerife is considered to be moderate, because eruptive frequency is low, explosivity is modest, and the eruptive activity of the Teide stratocone seems to have declined over the past 30 k.y., with only one eruption in this period (1150 yr B.P.)., This work has been possible thanks to the financial support of the Caja General de Ahorros de Canarias and the Spanish Plan Nacional de I+D+I research project CGL2005–00239/BTE. Financial support was also provided for the geochronological work by the Commisariat à ľÉnergie Atomique and Centre National de la Recherche Scientifique, France
Published: 2007
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27. Limited glaciation and very early deglaciation in central Iceland

Author: Brigitte Van Vliet-Lanoë, Bassam Ghaleb, Hervé Guillou, Philippe Recourt, Dominique Genty, Robert A. Duncan, Stéphane Scaillet, Sophie Gouy, and Agust Guðmundsson
Subjects: Global and Planetary Change, Eemian, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Pleistocene, Climate change, 010502 geochemistry & geophysics, 01 natural sciences, Oceanography, 13. Climate action, Deglaciation, Sea ice, General Earth and Planetary Sciences, Thermohaline circulation, Glacial period, Ice sheet, Geology, 0105 earth and related environmental sciences
Abstract: The sedimentary record of the Halslon dam, 20 km north of the Vatnajokull, allows a better understanding of the glaciation–deglaciation interface for MIS 6/5e and MIS2/1 in Northern Iceland. This sequence evidences the full Eemian deglaciation, the record of a Mid-Eemian cooling glacial complex and an abrupt deglaciation from the Bolling onward. Northern Iceland also experienced limited deglaciation and polar desert during the LGM, in connection with precipitation starvation due to the deflection towards the south of the Irminger current and of the Gulf Stream and the development of sea ice along the northern coastline.
Published: 2007
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28. The kinematics of central-southern Turkey and northwest Syria revisited

Author: Tuncer Demir, Stéphane Scaillet, Hervé Guillou, Tom S. White, Ali Seyrek, Rob Westaway, David R. Bridgland, Harran University, University of Glasgow, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), University of Cambridge [UK] (CAM), University of Oxford, Durham University, HÜBAK (the Harran University research development fund, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), and University of Oxford [Oxford]
Subjects: 010504 meteorology & atmospheric sciences, Pleistocene, Turkey, Pliocene, Active fault, Slip (materials science), Kinematics, Structural basin, 010502 geochemistry & geophysics, 01 natural sciences, Amik Basin, plate kinematics, Karasu Valley, 0105 earth and related environmental sciences, Earth-Surface Processes, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Subduction, Syria, Amanos Mountains, Geophysics, Plate kinematics, Submarine pipeline, Quaternary, Geology, Seismology
Abstract: International audience; Central-southern Turkey, NW Syria, and adjacent offshore areas in the NE Mediterranean region form the bound-ary zone between the Turkish, African and Arabian plates. A great deal of new information has emerged in recent years regarding senses and rates of active crustal deformation in this region, but this material has not hitherto been well integrated, so the interpretations of key localities by different teams remain contradictory. We have reviewed and synthesised this evidence, combining it with new investigations targeted at key areas of uncertain-ty. This work has led to the inference of previously unrecognised active faults and has clarified the roles of other structures within the framework of plate motions provided by GPS studies. Roughly one third of the relative mo-tion between the Turkish and Arabian plates is accommodated on the Misis–Kyrenia Fault Zone, which links to the study region from the Kyrenia mountain range of northern Cyprus. Much of this motion passes NNE then eastward around the northern limit of the Amanos Mountains, as previously thought, but some of it splays north-eastward to link into newly-recognised normal faulting within the Amanos Mountains. The remaining two thirds of the relative motion is accommodated along the Karasu Valley; some of this component steps leftward across the Amik Basin before passing southward onto the northern Dead Sea Fault Zone (DSFZ) but much of it continues southwestward, past the city of Antakya, then into offshore structures, ultimately linking to the subduction zone bounding the Turkish and African plates to the southwest of Cyprus. However, some of this offshore motion con-tinues southward, west of the Syrian coast, before linking onshore into the southern DSFZ; this component of the relative motion is indeed the main reason why the slip rate on the northern DSFZ, measured geodetically, is so much lower than that on its southern counterpart. In some parts of this region, notably in the Karasu Valley, it is now clear how the expected relative plate motion has been accommodated on active faults during much of the Quaternary: rather than constant slip rates on individual faults, quite complex changes in the partitioning of this motion on timescales of hundreds of thousands of years are indicated. However, in other parts of the re-gion it remains unclear whether additional major active faults remain unrecognised or whether significant rela-tive motions are accommodated by distributed deformation or on the many smaller-scale structures present.
Published: 2014
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29. Corrigendum to 'The kinematics of central-southern Turkey and northwest Syria revisited' [Tectonophysics 618 (2014) 35–66]

Author: Rob Westaway, Tuncer Demir, Stéphane Scaillet, Ali Seyrek, Hervé Guillou, Tom S. White, David R. Bridgland, Department of Soil Science, Department of Geography, Department of geography, Faculty of Mathematics and Computing, The Open University [Milton Keynes] (OU), School of Civil Engineering and Geosciences [Newcastle], Newcastle University [Newcastle], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Interpretation (philosophy), Mistake, 010502 geochemistry & geophysics, 01 natural sciences, Geological structure, [SHS]Humanities and Social Sciences, Geophysics, Seismic line, Tectonophysics, medicine, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Submarine pipeline, medicine.symptom, Relation (history of concept), Geology, Seismology, 0105 earth and related environmental sciences, Earth-Surface Processes, Confusion
Abstract: Refers to: Ali Seyrek, Tuncer Demir, Rob Westaway, Hervé Guillou, Stéphane Scaillet, Tom S. White, David R. Bridgland The kinematics of central-southern Turkey and northwest Syria revisitedTectonophysics, Volume 618, 31 March 2014, Pages 35-66, https://doi.org/10.1016/j.tecto.2014.01.008; International audience; The authors regret to inform that there is a need to make correction to the published article and the corrected text is provided here. We would like to apologise for any inconvenience caused.The Seyrek et al. (2014) synthesis of active crustal deformation in the northeast Mediterranean region combines offshore data with onshore evidence from central-southern Turkey and northwest Syria. The part of this synthesis integrating data from within and offshore of northwest Syria made extensive reference to Hardenberg and Robertson, 2007 and Hardenberg and Robertson, 2013. Part of this critique involved the presumption that the offshore seismic line located in Fig. 2 and depicted in Fig. 5 of Hardenberg and Robertson (2013) was in fact seismic line 5 of Vidal et al., 2000a and Vidal et al., 2000b, which Hardenberg and Robertson (2013) had plotted in the wrong place. However, subsequent discussions with Mat Hardenberg and Alastair Robertson have established, on the contrary, that they depicted a different seismic line. Thus, although there is no error in the Seyrek et al. (2014) interpretation of the geology or sense of active crustal deformation in the study region, a mistake was evidently made in the preparation of our paper, which this present note seeks to clarify.Given the current political situation, which makes additional substantive work in Syria unlikely for the foreseeable future, it is helpful to clarify the source of the above-mentioned confusion so mistakes arising from it do not propagate farther when research in Syria eventually resumes. We thus note, first, that Mat and Alastair have explained that the reference to ‘offshore seismic evidence’ on p. 234 of Hardenberg and Robertson (2007) is not to Vidal et al. (2000a), even though the latter is the only publication on seismic reflection data from the region immediately offshore of Syria that they cited, it is to an unpublished offshore dataset collected in 1975 by Spectrum Energy. Likewise, the acknowledgement on p. 468 of Hardenberg and Robertson (2013) that ‘We are grateful to Shell Syria for helping to sponsor the fieldwork and Spectrum Energy for providing access to 2D seismic data.’ is also referring to this 1975 seismic dataset, even though it does not say so and the wording in relation to fieldwork creates the impression that it relates to seismic data from somewhere onshore in Syria. Neither of the Hardenberg and Robertson (2013) figures that report seismic data makes any mention of Spectrum Energy and one of their captions refers to the Vidal et al., 2000a and Vidal et al., 2000b publications, seemingly confirming the impression of a connection with the latter when in reality no such link exists. The nature (indeed, the existence) of this 1975 seismic dataset only becomes evident on pp. 172–174 of Hardenberg (2003), although neither of the subsequent publications suggests that anyone might wish to read any part of this thesis for this information. In particular, the map in Fig. 4.3 on p. 173 of Hardenberg (2003) makes it clear that the seismic line discussed by Hardenberg and Robertson (2013) is Spectrum Energy line 24 S and the southern part of their line 24 N. Rather than showing the mis-plotting of any seismic line, Fig. 4 of Seyrek et al. (2014) can therefore now be regarded as an attempt to depict the relative positions, which no-one had previously illustrated, of this Spectrum Energy seismic line (in grey) and seismic line 5 of Vidal et al., 2000a and Vidal et al., 2000b (in purple), the mid-point of the latter being plotted ~ 8 km west of the southern end of the former. The similarities in the records from these two seismic lines confirm the continuity of the principal offshore geological structures in the region, this being the main reason why we looked into these seismic data in the first place.
Published: 2014
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30. Tephrochronology of the Mont-Dore volcanic Massif (Massif Central, France): new 40Ar/39Ar constraints on the Late Pliocene and Early Pleistocene activity

Author: Stéphane Scaillet, Jean-François Pastre, Pierre Nehlig, Vincent Scao, Sébastien Nomade, Hervé Guillou, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris 1 Panthéon-Sorbonne (UP1), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Panthéon-Sorbonne (UP1)
Subjects: geography, geography.geographical_feature_category, Explosive eruption, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, Mont-Dore Plio-Pleistocene 40Ar/39Ar Pyroclastic activity Flank collapse, Pyroclastic rock, Plio-Pleistocene, Massif, [SHS.GEO]Humanities and Social Sciences/Geography, Volcano, Geochemistry and Petrology, Pumice, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Stratovolcano, Mont-DorePlio-Pleistocene40Ar/39ArPyroclastic activityFlank collapse, Tephrochronology, Geomorphology, Geology, ComputingMilieux_MISCELLANEOUS
Abstract: International audience; The Mont-Dore Massif (500 km2), the youngest stratovolcano of the French Massif Central, consists of two volcanic edifices: the Guéry and the Sancy. To improve our knowledge of the oldest explosive stages of the Mont-Dore Massif, we studied 40Ar/39Ar-dated (through single-grain laser and step-heating experiments) 11 pyroclastic units from the Guéry stratovolcano. We demonstrate that the explosive history of the Guéry can be divided into four cycles of explosive eruption activity between 3.09 and 1.46 Ma (G.I to G.IV). We have also ascertained that deposits associated with the 3.1-3.0-Ma rhyolitic activity, which includes the 5-km3 "Grande Nappe" ignimbrite, are not recorded in the central part of the Mont-Dore Massif. All the pyroclastites found in the left bank of the Dordogne River belong to a later explosive phase (2.86-2.58 Ma, G.II) and were channelled down into valleys or topographic lows where they are currently nested. This later activity also gave rise to most of the volcanic products in the Perrier Plateau (30 km east of the Mont-Dore Massif); three quarters of the volcano-sedimentary sequence (up to 100 m thick) was emplaced within less than 20 ky, associated with several flank collapses in the northeastern part of the Guéry. The age of the "Fournet flora" (2.69 ± 0.01 Ma) found within an ash bed belonging to G.II suggests that temperate forests already existed in the French Massif Central before the Pliocene/Pleistocene boundary. The Guéry's third explosive eruption activity cycle (G.III) lasted between 2.36 and 1.91 Ma. It encompassed the Guéry Lake and Morangie pumice and ash deposits, as well as seven other important events recorded as centimetric ash beds some 60 to 100 km southeast of the Massif in the Velay region. We propose a general tephrochronology for the Mont-Dore stratovolcano covering the last 3.1 My. This chronology is based on 44 40Ar/39Ar-dated events belonging to eight explosive eruption cycles each lasting between 100 and 200 ky. The occurrence of only one pumice deposit in the 800-ky period between 1.9 and 1.1 Ma suggests that volcanic explosive activity was strongly reduced or quiescent.
Published: 2014
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31. Southeast Baffin volcanic margin and the North American-Greenland plate separation

Author: K. Perrot, Laurent Geoffroy, Jean-Paul Callot, Andrew G. Skuce, Jean-Pierre Gelard, C. Lepvrier, B. Bonin, C. Cayet, Stéphane Scaillet, M. Ravilly, and J. Angelier
Subjects: Basalt, geography, Dike, geography.geographical_feature_category, Lava, Mantle (geology), Tectonics, Paleontology, Geophysics, Volcano, Geochemistry and Petrology, Lithosphere, Geochronology, Geology, Seismology
Abstract: Plate breakup over plumes is characterized by the development of margins showing extensive magma production both underplated at Moho level and extruded as thick piles of seaward dipping lava formations. The Disko-Svartenhuk area in west Greenland is one of the few places in the world with exposed seaward dipping basalts forming a prism whose thickness increases seaward. We present a quantitative tectonic study of this margin, which we tentatively restored in its geodynamic position during the different stages of plate separation between Greenland and North America. Our structural data are constrained with recently published 39Ar/40Ar and new and coherent 40K/40Ar geochronology in dikes of different orientations. The first-order structure is that of a tectonically-driven seaward crustal flexure linked to definitive plate breakup between Greenland and Baffin Island during the Eocene, coeval with the formation of the upper part of the exposed seaward dipping volcanic prism. This flexing is associated with a significant crustal stretching associated with arrays of continentward dipping normal faults. This across-strike structure is correlated to a fundamental along-strike segmentation with the three “segments” adopting a “zigzag” strike. There is a clear increase of extensional strain at the extremities of the segments. Eocene extension trended N060 on average in the northern and southern segments but was NW trending in the central NE trending Nugssuaq segment. We discuss the interpretation of such an extension perpendicular to the different margin segments. From a regional point of view the N060 extension is distinct in orientation from the approximately N-S trend of plate separation between North America and Greenland in the Baffin Bay during the Eocene. However, the extension recorded in the margin is nearly perpendicular to the obliquely spreading Eocene accretion axis in the Baffin Bay. This latter point suggests a mantle or ridge control of the development of the margin over regional far-field lithospheric stress models.
Published: 2001
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32. Numerical error analysis in 40Ar/39Ar dating

Author: Stéphane Scaillet
Subjects: Propagation of uncertainty, Truncation error, Geology, Function (mathematics), Covariance, symbols.namesake, Geochemistry and Petrology, Approximation error, Taylor series, symbols, Partial derivative, Applied mathematics, Round-off error
Abstract: Calculation of an 40 Ar / 39 Ar age involves several sources of systematic (external) and statistic (mostly instrumental) errors that should be propagated into the final result for a proper statistical assessment of the age uncertainty and the overall resolution of the 40 Ar / 39 Ar dating technique. Error propagation is usually carried out by linearized error expansion techniques that weight the relative variance contribution of each input parameter by the squared partial derivative of the age function relative to this variable. Computation of partial derivatives through the working 40 Ar / 39 Ar equations is tedious and error-prone, however. As a result, several data reduction schemes using different levels of approximation are implemented in various laboratories, some of which ignore certain sources of error while others use simplified error equations, thus making direct comparison of published age and error estimates sometimes inaccurate. Based on the general numerical approach outlined by Roddick (1987) [Roddick, J.C., 1987. Generalized numerical error analysis with applications to geochronology and thermodynamics. Geochim. Cosmochim. Acta 51, 2129–2135], a complete 40 Ar / 39 Ar numerical error analysis (NEA) is proposed that includes up to 28 possible sources of error. The NEA code of Roddick (1987) is recast into a more rigorous central finite-difference (CFD) scheme, and applied to three non-ideal, worked 40 Ar / 39 Ar examples to test underpinning assumptions of the linearized error propagation by extending the error analysis to higher-order terms of the Taylor expansion of the age equation. Close to very close agreement between the analytic and numerical solutions suggests that the linearized error expansion technique is justified for 40 Ar / 39 Ar error propagation, despite strong nonlinearity in the related equations. In one pathological instance, nonlinearity is flagged by significant (15%) departure from the algebraic solution. The linearized age error estimate is still found to be acceptably close to the (exact) NEA estimate, provided however that covariance between 40 Ar * and 39 Ar K is precisely accounted for. As most 40 Ar / 39 Ar datasets will be invariably corrupted by large covariance corrections, a full-fledged error analysis as made possible through NEA is clearly desirable in most situations. The demonstrated flexibility of the numeric approach should be profitably extended to other areas of isotope geochemistry involving complex calculation codes such as treated here.
Published: 2000
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33. A revision of the structure and stratigraphy of pre-Green Tuff ignimbrites at Pantelleria (Strait of Sicily)

Author: Stéphane Scaillet, Silvio G. Rotolo, Grazia Vita-Scaillet, Sonia La Felice, Dipartimento di Chimica e Fisica della Terra [Palermo], Università degli studi di Palermo - University of Palermo, Instituto Nationale di Geofisica e Vulcanologia (INGV), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Rotolo, S., Scaillet, S., La Felice, S., Vita Scaillet, G., Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: pantellerite, 010504 meteorology & atmospheric sciences, Lava, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, Silicic, Pyroclastic rock, 010502 geochemistry & geophysics, 01 natural sciences, Peralkaline rock, 40Ar/39Ar dating, Geochemistry and Petrology, Pumice, peralkaline magma, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, Peralkaline magmas, Geomorphology, 0105 earth and related environmental sciences, Ignimbrites, Settore GEO/07 - Petrologia E Petrografia, Strombolian eruption, ignimbrite, Geophysics, Dense-rock equivalent, Pantellerites, Geology, Pantelleria
Abstract: International audience; At Pantelleria, peralkaline silicic magmas were erupted across a range of eruptive typologies and magnitudes: pyroclastic flows, Plinian to strombolian pumice fallout and lava flows. In this paper we focus on the intermediate cycle of eruptive activity which is bracketed by ignimbrite units slightly older than the two caldera collapses which marked the volcanological activity of the island. This age interval (180-85 ka) was punctuated by six ignimbrite-forming eruptions (silicic and variably peralkaline) for a cumulative erupted magma volume of approximately 6 km3 dense rock equivalent. Based on new 40Ar/39Ar (Na,K)-feldspar ages and petrographic data, we propose an updated volcanostratigraphic scheme for these welded and rheomorphic ignimbrites that can be summarised as follows: (i) the age of the old ('La Vecchia') caldera collapse is now tightly constrained between 140 and 146 ka and the caldera-forming eruption can be traced to a lithic-rich welded tuff breccia that outcrops in two opposite sectors of the island (south-west and north-east); (ii) four ignimbrite units previously considered unrelated are now merged in two distinct eruptive paroxysmal events at 107 and 85 ka. In particular, the 85 ka eruptive event is comparable in magnitude to the younger (caldera forming) Green Tuff Plinian eruption; (iii) the recurrence patterns of the 107 and 85 ka eruptions, compared to the Green Tuff, allow us to qualitatively assess that the climax in production of low-temperature silicic and peralkaline melt was focused in the age interval 85-45 ka.
Published: 2013
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34. Millennial-scale phase relationships between ice-core and Mediterranean marine records: insights from high-precision 40Ar/39Ar dating of the Green Tuff of Pantelleria, Sicily Strait

Author: Grazia Vita-Scaillet, Silvio G. Rotolo, Stéphane Scaillet, Scaillet, S., Vita Scaillet, G., Rotolo, S., Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Dipartimento di Chimica e Fisica della Terra [Palermo], Università degli studi di Palermo - University of Palermo, Instituto Nationale di Geofisica e Vulcanologia (INGV), and GVS was supported through a personnel grant from INGV-DPC Project 2005-2007, V3-3. Field and laboratory work was partly supported through an INGV-DPC grant (Project 2005-2007, V3-7 'Pantelleria')
Subjects: Archeology, 010504 meteorology & atmospheric sciences, Marker horizon, Ar/Ar dating, [SDE.MCG]Environmental Sciences/Global Changes, Radioisotopic timescale, 010502 geochemistry & geophysics, Geologic record, 01 natural sciences, law.invention, Paleontology, Ice core, law, Absolute dating, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Green Tuff, 14. Life underwater, Radiocarbon dating, Tephra, Ecology, Evolution, Behavior and Systematics, Radioisotopic timescale, Green Tuff, Pantelleria, Tephrochronology, Ar/Ar dating, 0105 earth and related environmental sciences, Global and Planetary Change, Settore GEO/07 - Petrologia E Petrografia, Geology, Settore GEO/08 - Geochimica E Vulcanologia, Tephrochronology, Quaternary, Pantelleria
Abstract: International audience; With the advent of annually-resolved polar ice records extending back to 70 ka, marine and continental paleoclimate studies have now matured into a discipline where high-quality age control is essential for putting on an equal pace layer-counted timescale models and Late Quaternary sedimentary records. High-resolution U-Th dating of speleothem records and 40Ar/39Ar dating of globally recorded geomagnetic excursions have recently improved the time calibration of Quaternary archives, reflecting the cross-disciplinary effort made to synchronize the geologic record at the millennial scale. Yet, tie-points with such an absolute age control remain scarce for paleoclimatic time-series extending beyond the radiocarbon timescale, most notably in the marine record. Far-travelled tephra layers recorded both onland and offshore provide an alternative in such instance to synchronize continental and marine archives via high-resolution 40Ar/39Ar dating of the parent volcanic eruption. High-resolution 40Ar/39Ar data are reported herein for one such volcanic marker, the Green Tuff of Pantelleria and its Y-6 tephra equivalent recorded throughout the Central and Eastern Mediterranean. Published radiochronometric and δ18O orbitally-tied ages for this marker horizon scatter widely from about 41 ka up to 56 ka. Our new 40Ar/39Ar age at 45.7 ± 1.0 ka (2σ) reveals that previous estimates are biased by more than their reported errors would suggest, including recent orbital tuning of marine records hosting the tephra bed that are reevaluated in the context of this study. This improved estimate enables potential phase lags and leads to be studied between deep-sea and terrestrial archives with unrivaled (near-millennial) 40Ar/39Ar precision in the marine record.
Published: 2013
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35. Evolution of the crustal magma plumbing system during the build-up to the 22-ka caldera-forming eruption of Santorini (Greece)

Author: Gareth N. Fabbro, Stéphane Scaillet, Timothy H. Druitt, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Basalt, Explosive eruption, Santorini, 010504 meteorology & atmospheric sciences, biology, Andesites, [SDE.MCG]Environmental Sciences/Global Changes, Calderas, Geochemistry, Silicic, Crust, 010502 geochemistry & geophysics, Dacite, biology.organism_classification, 01 natural sciences, Crystal residence timescales, 13. Climate action, Geochemistry and Petrology, Magma, Magma reservoirs, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, Melt accumulation, Geology, 0105 earth and related environmental sciences
Abstract: International audience; The formation of shallow, caldera-sized reservoirs of crystal-poor silicic magma requires the generation of large volumes of silicic melt, followed by the segregation of that melt and its accumulation in the upper crust. The 21.8 ± 0.4-ka Cape Riva eruption of Santorini discharged >10 km3 of crystal-poor dacitic magma, along with
Published: 2013
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36. Excess 40Ar transport scale and mechanism in high-pressure phengites: A case study from an eclogitized metabasite of the Dora-Maira nappe, western Alps

Author: Stéphane Scaillet
Subjects: Basement, education.field_of_study, Geochemistry and Petrology, Greenschist, Population, Geochemistry, Metamorphism, Eclogite, education, Protolith, Geology, Nappe, Phengite
Abstract: Application of the bulk-separate furnace heating, laser step-heating, and in situ laser agemapping 40Ar/39Ar techniques reveals that high-pressure phengites from an Alpine eclogite of the Dora-Maira basement nappe, western Alps, were pervasively contaminated with excess 40Ar to yield ages > 130 Ma. Spot-fusion dating of individual grains with the 40Ar/39Ar laserprobe reveals concentric radial patterns with core ages as high as 320 Ma, showing that this excess component was trapped at an early stage and subsequently remobilized by volume diffusion during a late greenschist thermal pulse. The single grains and population from this hand-sample retain major differences in apparent ages indicating that the extent of the excess 40Ar contamination varies from grain to grain. Attempt to model these differences in terms of grain-size-dependent fractional loss falls short and demonstrates that strong cm-scale argon isotopic gradients locally prevailed during syn-kinematic high-pressure metamorphism. On petrostructural grounds, a model of internal isotopic buffering is outlined, whereby the excess 40Ar is argued to have been internally derived from within the eclogite protolith itself. Low intergranular Ar diffusion rates due to reduced water activity (buffered below unity by the phengite assemblage) resulted in the local segregation and partitioning of the excess 40Ar along grain boundaries during ongoing ductile deformation. Supporting evidence for this model comes from the recent literature on fluid and stable isotope behaviour in Alpine eclogites and very-high-pressure metasediments, which shows that volatile recycling during high-pressure metamorphism may occur on a very limited scale.
Published: 1996
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37. Late Cenozoic regional uplift and localised crustal deformation within the northern Arabian Platform in southeast Turkey: Investigation of the Euphrates terrace staircase using multidisciplinary techniques

Author: Ant Beck, Rob Westaway, Tuncer Demir, David R. Bridgland, Hervé Guillou, Ali Seyrek, Stéphane Scaillet, Harran University, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), University of Leeds, Durham University, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Milankovitch cycles, 010504 meteorology & atmospheric sciences, Pleistocene, Anticline, Fluvial, Late Miocene, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, 13. Climate action, Aggradation, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Cenozoic, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Chronology
Abstract: We present the results of detailed field investigations of the fluvial succession exposed along the Euphrates valley adjoining the Ataturk Dam in the northern part of the Arabian Platform within SE Turkey. This work, which has used Differential GPS surveying to obtain accurate heights of deposits and Shuttle Radar Topographic Mission imagery for location purposes, has included documentation of many fresh sections exposed by quarrying. The work has been supplemented by unspiked KAr dating of late Middle Miocene to Late Miocene basalt flows, which are widespread in the region, providing a chronology for the early stages of development of this river system following regional emergence above sea-level in the early Middle Miocene. For example, beside the Ataturk Dam Lake at Siverek Iskelesi, basalt dated to 10.24 ± 0.22 Ma (± 2σ) caps a polymict Euphrates gravel some 80 m above the modern river; this is the oldest Euphrates terrace currently recognised. However, amounts and rates of fluvial incision are shown to vary across the northern Arabian Platform in a complex manner, due to the interaction between regional uplift and localised vertical crustal motions caused by slip on active reverse faults beneath anticlines. The study reach downstream of the Ataturk Dam includes the footwall of one such fault, beneath the Bozova Anticline; we estimate that the resulting rate of localised subsidence, superimposed onto the regional uplift that has also been occurring, has been ~ 0.01 mm a− 1 during the present phase of crustal deformation, which began at ~ 3.7–3.6 Ma, but was higher, maybe ~ 0.03 mm a− 1, during the previous phase, which began at ~ 6 Ma, when the pattern of plate motions in the surrounding region was different. A large palaeo-lake centred north of the present study region around the city of Adiyaman is inferred to have existed during this ~ 6 Ma to ~ 3.7–3.6 Ma phase of plate motion, apparently because the relatively rapid localised hanging-wall uplift on the northern flank of the Bozova Anticline ‘dammed’ the Euphrates valley near the site of the modern Ataturk Dam. The uppermost part of a thick fluvial aggradation west of the Euphrates near Karababa Bridge, inferred to date from around the Mid Pliocene, reaches ~ 100 m above the modern river and, after correction for an estimated ~ 30 m of localised subsidence and by ~ 50 m for subsequent downstream lengthening of the Euphrates channel, indicates ~ 180 m of subsequent regional uplift. The Euphrates then incised to within ~ 20 m of its present level by the mid Early Pleistocene, then a switch to regional subsidence accompanied the deposition of a second thick fluvial aggradation, the top of which is ~ 70 m above the modern river. Subsequent renewed regional uplift, following the Mid-Pleistocene Revolution, has resulted in the development of a succession of fluvial terraces, typically inset into these older aggradations, which are correlated with the cold stages of Milankovitch climate cycles. The early part of the Euphrates chronology, constrained mainly by the disposition of basalt flows, indicates ~ 800 m of regional uplift since the early Middle Miocene, of which an estimated ~ 330 m is masked by the subsequent downstream lengthening of the river. Components of localised uplift and subsidence, caused by slip on reverse faults beneath anticlines, are superimposed onto this regional pattern, the hanging-wall uplift being much larger (in one case, roughly five times larger) than the footwall subsidence. Our results provide, for the first time, detailed documentation of the complex development of the Euphrates valley in SE Turkey during the Late Cenozoic, due to the interaction between regional uplift and localised crustal deformation. This work also demonstrates the benefits of applying multidisciplinary techniques to investigate an important, but hitherto poorly documented, river system.
Published: 2012
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38. Constraints on the timing and regional conditions at the start of the present phase of crustal extension in western Turkey, from observations in and around the Denizli region

Author: George Rowbotham, Tuncer Demir, Hervé Guillou, Rob Westaway, Sema Yurtmen, Stéphane Scaillet, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Newcastle University [Newcastle], Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Cukurova University, Harran University, Keele University [Keele], and Çukurova Üniversitesi
Subjects: Pliocene, Turkey, 010504 meteorology & atmospheric sciences, Volcanism, 010502 geochemistry & geophysics, 01 natural sciences, Uplift, Quaternary, K-Ar dating, Paleontology, Extension, parasitic diseases, skin and connective tissue diseases, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, integumentary system, Continental crust, food and beverages, K–Ar dating, Miocene, 15. Life on land, Geophysics, 13. Climate action, Seismology, Geology, Chronology
Abstract: The chronology of extension of the continental crust in western Turkey has been the subject of major controversies. We suggest that these difficulties have arisen in part because of past misuse of dating evidence; and in part because the assumption often made, that deposition of major terrestrial sedimentary sequences implies crustal extension to create the necessary accommodation space, is incorrect. We report evidence that the present phase of extension began in the Denizli region at ~ 7 Ma, around the start of the Messinian stage of the Late Miocene. This timing matches the estimated start of right-lateral slip on the North Anatolian Fault Zone, and corresponds to a substantial increase in the dimensions of the Aegean extensional province to roughly its present size: beforehand, between ~ 12 Ma and ~ 7 Ma, extension seems to have only occurred in the central part of this modern province. In some localities, terrestrial sedimentation that began before this start of extension continued into this extensional phase, both within and outside normal fault zones. However, in other localities within the hanging-walls of normal faults, the start of extension marked the end of sedimentation. Relationships between sedimentation and crustal extension in this region are thus not straightforward, and a simple correlation should therefore not be assumed in structural interpretations. During the time-scale of this phase of extension, the Denizli region has also experienced major vertical crustal motions that are unrelated to this extension. The northern part of this region, in the relatively arid interior of western Turkey, has uplifted by ~ 400 m since the Middle Pliocene, whereas its southern part, closer to the Mediterranean Sea and with a much wetter climate, has uplifted by ~ 1,200 m since the Early Miocene, by up to ~ 900 m since the Middle Pliocene, and by an estimated ~ 300 m since the Early Pleistocene. This regional uplift, superimposed on the local effects of active normal faulting, is interpreted as a consequence of lateral variations in rates of erosion. A reliable chronology for this phase of extension in western Turkey, in relation to changes in the geometry of motions of adjoining plates and Late Cenozoic environmental change, is now in place. © 2005 Taylor & Francis Group, LLC.
Published: 2012
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39. Pyroclastic chronology of the Sancy stratovolcano (Mont-Dore, French Massif Central): New high-precision Ar-40/Ar-39 constraints

Author: Pierre Nehlig, Jean-François Pastre, Stéphane Scaillet, Sébastien Nomade, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, Pyroclastic rock, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Ar-40/Ar-39, 010502 geochemistry & geophysics, Stratovolcano, 01 natural sciences, Geochemistry and Petrology, Pumice, Caldera, Pyroclastites, Tephra, Geomorphology, 0105 earth and related environmental sciences, Sancy, geography, geography.geographical_feature_category, Residence time, Massif, Pleistocene, Geophysics, Volcano, 13. Climate action, Magma, Geology
Abstract: International audience; The Sancy (16 km(2)) is the youngest of the two stratovolcanoes that constitute the Mont-Dore Massif (Massif Central, France). The restricted number of high precision radio-isotopic ages currently limits our knowledge of the pyroclastic chronology of this edifice which is the source of many tephra layers detected in middle Pleistocene sequences in southeast Europe. To improve our knowledge of the building phases of this stratovolcano, we collected thirteen pyroclastic units covering the entire proximal record. We present Ar-40/Ar-39 single grain laser dating performed in the facility hosted at the LSCE (Gif-sur-Yvette, France). The Ar-40/Ar-39 ages range from 1101 +/- 11 ka to 392 +/- 7 ka (his external). Four pyroclastic cycles lasting on average 100 ka were identified (C. I to C. IV). C. I corresponds to the earlier explosive phase between 1101 ka and 1000 ka and starts about 100 ka earlier than previously thought. The second pyroclastic cycle (C. II) is the main pyroclastic episode spanning from 818 to 685 ka. This cycle is constituted of a minimum of 8 major pyroclastic eruptions and includes a major event that corresponds to a large plinian eruption at 719 +/- 10 ka (1 sigma external) and recorded as a 1.4 m thick layer 60 km south-east of the Sancy volcano. The link between this large eruption and formation of a caldera stays however, hypothetical. The third pyroclastic cycle (C. III) found in the northeastern part of the Sancy (Mont-Dore valley) spanned from 642 to 537 ka. Finally, the youngest pyroclastic cycle (C. IV) starts at 392 ka and probably ends around 280 ka. The age versus geographic location of each pyroclastic cycle indicates three preferential directions of channeling of the pyroclastic events and/or collapse of the volcanic edifice: northwest to west (C. l), southeast (C. II) and finally north to northeast (C. III and IV). The new high precision Ar-40/Ar-39 age for the Queureuilh bas pyroclastic unit (642 +/- 9 ka) is identical within error with the U/Pb age obtained by Cocherie et al. (2009) [Geochimica et Cosmochimica Acta, 73, 1095-1108] and suggests a short residence time of the magma in a shallow, short-lived, small magmatic chamber. Finally, the source of the t21d tephra layer found in the Pianico Sellere varved sequence (Northern Italy) is not the Rivaux pumice flow as proposed by Brauer et al. (2007) [Journal of Quaternary Science 22, 85-96] and neither one of the C. II pyroclastic units as suggested by Roulleau et al. (2009) [Quaternary International 204,31-43]. Accordingly, the source for the t21d layer has yet to be found at Sancy or elsewhere.
Published: 2012
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40. High-resolution 40Ar/39Ar chronostratigraphy of the post-caldera (<20 ka) volcanic activity at Pantelleria, Sicily Strait

Author: Silvio G. Rotolo, Grazia Vita-Scaillet, Sonia La Felice, Stéphane Scaillet, Scaillet, S., Rotolo, S., LA FELICE, S., Vita, G., Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Silicic, Forcing (mathematics), 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Caldera, Chronostratigraphy, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, 40Ar/39Ar xenocrysts excess 40Ar anorthoclase, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Horizon (geology), geography, geography.geographical_feature_category, Settore GEO/07 - Petrologia E Petrografia, Subsidence, Paleosol, Settore GEO/08 - Geochimica E Vulcanologia, Geophysics, Volcano, 13. Climate action, Space and Planetary Science, Geology
Abstract: The island of Pantelleria (Sicily Strait), the type locality for pantellerite, has been the locus of major caldera-forming eruptions that culminated, ca. 50 ka ago, in the formation of the Cinque Denti caldera produced by the Green Tuff eruption. The post-caldera silicic activity since that time has been mostly confined inside the caldera and consists of smaller-energy eruptions represented by more than twenty coalescing pantelleritic centers structurally controlled by resurgence and trapdoor faulting of the caldera floor. A high-resolution 40Ar/39Ar study was conducted on key units spanning the recent (post-20 ka) intracaldera activity to better characterize the present-day status (and forecast the short-term behavior of) the system based on the temporal evolution of the latest eruptions. The new 40Ar/39Ar data capture a long-term (> 15 ka) decline in eruption frequency with a shift in eruptive pace from 3.5 ka−1 to 0.8 ka−1 associated with a prominent paleosol horizon marking the only recognizable volcanic stasis around 12–14 ka. This shift in extraction frequency occurs without major changes in eruptive style, and is paralleled by a subtle trend of decreasing melt differentiation index. We speculate that this decline probably occurred (i) without short-term variations in melt production/differentiation rate in a steady-state compositionally-zoned silicic reservoir progressively tapped deeper through the sequence, and (ii) that it was possibly modulated by outboard eustatic forcing due to the 140 m sea level rise over the past 21 ka. The intracaldera system is experiencing a protracted stasis since 7 ka. Coupled with recent geodetic evidence of deflation and subsidence of the caldera floor, the system appears today to be on a wane with no temporal evidence for a short-term silicic eruption.
Published: 2011
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41. Quaternary volcano-lacustrine patterns and palaeobotanical data in southern Armenia

Author: Paul Roiron, Wout Krijgsman, Vincent Ollivier, Stéphane Scaillet, Christine Chataigner, Ivan Gabrielyan, Boris Gasparyan, Jean-Jacques Cornée, Hervé Guillou, Philippe Münch, Samuel Nahapetyan, Sébastien Joannin, Laboratoire méditerranéen de préhistoire Europe-Afrique (LAMPEA), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture (MC), ARCHEORIENT - Environnements et sociétés de l'Orient ancien (Archéorient), Université Lumière - Lyon 2 (UL2)-Centre National de la Recherche Scientifique (CNRS), Centre de Bio-Archéologie et d'Ecologie (CBAE), Université Montpellier 2 - Sciences et Techniques (UM2)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), PaleoEnvironnements et PaleobioSphere (PEPS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Maison des Sciences de l'Homme et de l'Environnement Claude Nicolas Ledoux (MSHE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Paleomagnetic Laboratory ‘Fort Hoofddijk', Utrecht University, Faculty of Geosciences, Utrecht University [Utrecht], Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Montpellier 2 - Sciences et Techniques (UM2), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Maison des Sciences de l'Homme et de l'Environnement Claude Nicolas Ledoux (UAR 3124) (MSHE), Laboratoire méditerranéen de préhistoire Europe-Afrique ( LAMPEA ), Aix Marseille Université ( AMU ) -Ministère de la Culture et de la Communication ( MCC ) -Institut national de recherches archéologiques préventives ( Inrap ) -Centre National de la Recherche Scientifique ( CNRS ), ARCHEORIENT - Environnements et sociétés de l'Orient ancien ( Archéorient ), Université Lumière - Lyon 2 ( UL2 ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de Bio-Archéologie et d'Ecologie ( CBAE ), Université Montpellier 2 - Sciences et Techniques ( UM2 ) -École pratique des hautes études ( EPHE ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Paléoenvironnement et paléobiosphère ( PP ), Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Maison des Sciences de l'Homme et de l'Environnement Claude Nicolas Ledoux ( MSHE ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Université des Antilles et de la Guyane ( UAG ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] ( LSCE ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chimie de l'environnement ( LCE ), Centre National de la Recherche Scientifique ( CNRS ) -Aix Marseille Université ( AMU ), Université Montpellier 2 - Sciences et Techniques (UM2)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement (UMR 6249) (LCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010506 paleontology, education.field_of_study, geography, geography.geographical_feature_category, Pleistocene, Lava, Population, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Glacier, [ SDU.STU ] Sciences of the Universe [physics]/Earth Sciences, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, [ SHS.ENVIR ] Humanities and Social Sciences/Environmental studies, Paleontology, Volcano, [SHS.ENVIR]Humanities and Social Sciences/Environmental studies, Radiometric dating, education, Quaternary, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes, Chronology
Abstract: International audience; The morphogenetic evolution of the Lesser Caucasus has been strongly influenced by Plio-Quaternary volcanic and tectonic events and Pleistocene glaciations. Fluvio-lacustrine environments, indicated by diatomaceous deposits, prevailed in the Syunik region of southern Armenia during the Pliocene and Pleistocene. The Pleistocene diatomaceous deposits studied contain leaf impressions and pollen, allowing local palaeoclimatic reconstructions. The chronology of morphogenetic events has been determined by 17 radiometric dates (K/Ar, Ar/Ar, U/Th), palaeomagnetic investigations and is placed in a spatial context by a detailed geomorphological map and a 24-km geological transect of the Vorotan valley, the main area studied. Before 1.21 Ma, tectonic movements (antecedents of the lower part of the Vorotan valley) generated extensive lake formations with diatomaceous deposits. From 993 ka, volcanic eruptions produced lava flows that covered the fluvio-lacustrine accumulations. During Marine Isotopic Stages 12, 6 and 4, glaciers and fluvio-glacial deposits were probably present overall the principal uplands and valleys of southern Armenia. At 53.68 ka (MIS 3), 12.6 ka, 10.78 ka and 4.14 ka (MIS 1), the development of travertines on some slopes and in some valleys highlights temperate and humid climatic phases. Palaeobotanical studies of leaf and pollen floras show that the vegetation changed several times from forested to steppic phases in response to the climate oscillations of the Lower Pleistocene. This work proposes a first morphogenic and palaeoclimatic reconstruction from the lower Pleistocene to the Postglacial period, when the first settlements of the population in the Lesser Caucasus were influenced by tectono-volcanic events, lake level changes and glacialeinterglacial oscillations forced by the obliquity orbital parameter (41 ky cycles).
Published: 2010
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42. Indicateurs morphosédimentaires des variations de niveau lacustre dans les terrasses du lac de Van (Turquie)

Author: Michel Fontugne, Ebru Akköprü, Aurélien Christol, Mustafa Karabıyıkoğlu, Ali Fuat Doğu, Damase Mouralis, Halil Zorer, Stéphane Scaillet, Daniel Brunstein, Monique Fort, Catherine Kuzucuoğlu, Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Identités et Différenciation de l'Environnement des Espaces et des Sociétés (IDEES), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Institut de Recherche Interdisciplinaire Homme et Société (IRIHS), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Université de Van, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochrononologie Traceurs Archéométrie (GEOTRAC), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: 010506 paleontology, Lake Van, sedimentology, Geology, Lac de Van, [SHS.GEO]Humanities and Social Sciences/Geography, Upper Pleistocene, Pléistocène supérieur, 010502 geochemistry & geophysics, 01 natural sciences, niveaux lacustres, Terraces, Eastern Anatolia, Geography, 13. Climate action, lake levels, Anatolie orientale, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, lac de Van, sédimentologie, Humanities, terrasses, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: Le lac de Van, dans les montagnes d’Anatolie orientale, ne possède pas d’exutoire naturel. Malgré son volume (604 km3), les amplitudes des variations de son niveau témoignent, depuis 1944, d’une sensibilité élevée aux fluctuations hydro-climatiques. Dans cette perspective, les dépôts hérités d’anciens hauts niveaux, conservés sous forme de terrasses côtières dans les parties aval anciennement immergées des affluents du lac, permettent d’identifier, de caractériser et de dater les changements de volume d’eau lacustre qu’ont enregistrés les sédiments qui sous-tendent ces terrasses. Plusieurs travaux récents sur les sédiments du fond du lac de Van ont mis en évidence leur intérêt exceptionnel pour la reconstitution des paléoclimats et permis de détailler l’évolution paléoenvironnementale du Tardiglaciaire et de l’Holocène. Cependant, les études des dépôts lacustres émergés restent rares. Ces dépôts font l’objet ici d’une étude géomorphologique de terrain couplée à des caractérisations sédimentologiques de faciès, des mesures altimétriques DGPS, des reconstitutions spatialisées et la mise en place des premiers jalons d’une chronostratigraphie basée sur des datations14C de dépôts organiques et coquilles, 39Ar/40Ar de tephras, et U-Th de travertins. Dans l’attente de datations OSL, nos résultats préliminaires permettent d’identifier au moins deux cycles de transgression, datés respectivement du début du dernier Glaciaire et d’une période couvrant le Dernier Maximum Glaciaire (DMG). Chaque cycle correspond à une phase de transgression rapide, suivie de variations intermédiaires d’amplitude plus ou moins forte, et se terminant par une longue phase de régression par paliers. La cause de ces variations et, notamment, la part qu’y a prise le climat est évidente pour le cycle datant du DMG, mais l’est moins pour celui marquant le début du Glaciaire dont les liens avec le volcanisme et la tectonique sont étroits. La forte instabilité de la paléogéographie est liée au volcanisme qui est à l’origine de barrages ayant entraîné la fermeture du bassin versant du lac. In the eastern Anatolian Mountains, the relatively high-magnitude variations exhibited by the level of Lake Van in recent years indicate, as the lake has no outlet, that this level can be considered as a sensitive indicator of climate if these variations respond to changes in water input/output. Until now, previous palaeoclimatic research has focused mainly on deep sediments in the lake, which provided an environmental sequence which is today a reference for the Late Glacial and the Holocene in the Middle East. In spite of many landforms and deposits around the lake pointing out to the occurrence of very high levels in the past, studies on the lacustrine sediments preserved in terrace records around the lake have remained quite rare since a frst exhaustive overview realized in the l970’s. We here present the frst results of a field work coupled with sedimentology studies (stratigraphy, facies analyses), DGPS elevation measurements, spatialized reconstructions. Chronostratigraphy takes advantage of the presence of interstratified tephras layers dated by 39Ar/40Ar, of travertines dated by U-Th series, as well as of organic deposits and shells dated by 14C. Results evidence the occurrence of two major and rapid transgressions, the first one happening at the beginning of the Last Glacial, the second one in the millennia preceding the Last Glacial Maximum (LGM). Each identified lacustrine cycle started with a very rapid transgression followed by slower regressions with intermediate oscillations. Regressions started immediately after the highest stand was reached (+80 m and +55 m). Regressions lasted long, with some stand-by during the descent, allowing erosion surfaces to truncate the surface of the emerging lake deposits. During Upper Pleistocene, tectonic and volcanic activities interfered with the climatic record of lake levels, both by deforming deposits locally (uplift, faulting) and by modifying the drainage area and river network of the lake basin (closure by damming, captures, isolation). Our preliminary results thus enlighten the complexity of the processes triggering the high magnitude transgressions of the Upper Pleistocene Van Lake, as well as the difficulty to establish correspondences between climatic changes and water volume changes as evidenced by past shoreline deposits preserved in the terrace sedimentary records.
Published: 2010
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43. Miocene to Messinian deformation and hydrothermal activity in a pre-alpine basement massif of the French Western Alps: New U-Th-Pb and Argon ages from the Lauzière massif

Author: Stéphane Scaillet, Sébastien Nomade, Jean-Louis Paquette, Jean-Michel Bertrand, Anne-Marie Boullier, Jérémie Lehmann, Gueorgui Ratzov, Roger De Ascenção Guedes, Dominique Gasquet, Massimo Tiepolo, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Laboratoire Magmas et Volcans (LMV), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Centre de géochimie de la surface (CGS), Centre National de la Recherche Scientifique (CNRS)-Université Louis Pasteur - Strasbourg I-Institut national des sciences de l'Univers (INSU - CNRS), Géoazur (GEOAZUR 6526), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Istituto di Geoscienze e Georisorse (IGG), Consiglio Nazionale delle Ricerche [Roma] (CNR), Mécanique des failles, Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), 'BQR' grant ('Chro-noréférencement'), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, and Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: geography, U-Pb and Ar-Ar geochronology, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, External crystalline, Western Alps, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, Geology, Massif, Miocene, Late Miocene, 010502 geochemistry & geophysics, Strike-slip tectonics, Fission track dating, 01 natural sciences, Lauzière, Nappe, Hydrothermal veins, Lineation, Vein (geology), Geomorphology, 0105 earth and related environmental sciences, Mylonite
Abstract: U-Pb and Th-Pb dating of monazite from hydrothermal quartz veins (“Alpine veins”) from the Lauzière massif (North Belledonne) together with Ar/Ar ages of adularias from the same veins constrain the age of the last tectono-metamorphic events that affected the External Crystalline Massifs (ECM). Ages obtained are surprisingly young. The study of the structural context of the veins combined with our chronological data, allow us to propose a tectonic scenario of the northern ECM for the 15-5 Ma period, which was poorly documented so far. The quartz veins are of two types: (i) the oldest are poorly mineralized (chlorite and epidote), flat-lying veins. The quartz fibres (= extension direction) are near vertical and seem to be associated with a subvertical dissolution schistosity superimposed upon an early Alpine deformation underlined by “mini-biotite”. They bear a sub-horizontal stretching lineation; (ii) the youngest veins are very rich in various minerals (anatase, rutile, phénacite, meneghinite, beryl, synchysite, ….). They are almost vertical. Their “en echelon” geometry as well as the horizontal attitude of their quartz fibres show a dextral strike-slip regime. Two groups of Th-Pb ages have been obtained: 11 to 10 Ma and 7 to 5 Ma. They were obtained from the most recent veins (vertical veins) sampled in different areas of the massif. The ca. 10 Ma ages are related to veins in the Lauzière granite and its metamorphic country-rocks at about 2 km from the eastern contact of the massif, while the ages of ca. 5 Ma correspond to veins occurring in mylonites along this contact. Adularias provided Ar/Ar ages at ca. 7 Ma. By contrast, a monazite from a vein of the Pelvoux massif (Plan du Lac) yielded a Th-Pb age of 17.6 Ma but in a different structural setting. Except fission track ages, there are very little ages of this range published in the recent literature on the Alps. The latter concern always gold mineralized veins (NE Mont Blanc and SW Lepontine dome). The last compressive tectonic regime dated between 15 and 12 Ma is coeval with (i) the late “Roselend thrust” event, which is recorded in the Mont Blanc by shear-zones with vertical lineation, (ii) the last movements in the basal mylonites of the Swiss Nappes, (iii) the horizontal Alpine veins from the Mont Blanc and Belledonne massifs (with vertical quartz fibres), which are similar to the early veins of the Lauzière. On the contrary, the vertical veins of the Lauzière, dated between 11 and 5 Ma, correspond to a dextral strike slip regime. This suggests that most of the strike-slip tectonics along the ECM took place during two stages (ca. 10 Ma and ca. 7-5 Ma) and not only at 18 Ma as had been proposed previously. Our ages are consistent with the late Miocene-Pliocene overlap of the Digne thrust to the South and to part of the normal movement along the Simplon fault to the North. Thus, all the external crystalline massifs were tectonically active during the late Miocene. This suggests that tectonic events in the external alpine belt may have contributed to some extent to the geodynamical causes of the Messinian crisis.
Published: 2010
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44. The pyroclastites around southwestern part of Van Lake (eastern Anatolia, Turquey): implications on the regional palaeohydrography

Author: Aurélien Christol, Hervé Guillou, Catherine Kuzucuoğlu, Ali Fuat Doğu, Damase Mouralis, Daniel Brunstein, Halil Zorer, Stéphane Scaillet, Monique Fort, Ebbru Akköprü, Identités et Différenciation de l'Environnement des Espaces et des Sociétés (IDEES), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Institut de Recherche Interdisciplinaire Homme et Société (IRIHS), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-AgroParisTech-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Van, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Sorbonne (UP4)-École pratique des hautes études (EPHE)-Institut de Recherche pour le Développement (IRD)-Université Panthéon-Sorbonne (UP1), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris 1 Panthéon-Sorbonne (UP1), Istanbul University, Yüzüncü Yıl University, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG (UMR_8586 / UMR_D_215 / UM_115)), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-AgroParisTech-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: 010504 meteorology & atmospheric sciences, Lac de Van, Téphrostratigraphie, 010502 geochemistry & geophysics, Paléo-hydrographie, 01 natural sciences, [SHS]Humanities and Social Sciences, Phanerozoic, Palaeo-hydrography, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Anatolia, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, Tephrostratigraphy, Van Lake, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Anatolie, Geology, [SHS.GEO]Humanities and Social Sciences/Geography, 15. Life on land, Tephra, Téphra, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, [SDE]Environmental Sciences, Quaternary, Cenozoic, Humanities
Abstract: International audience; Located in eastern Anatolia (Turkey), Lake Van is the fourth largest lake in the world. Along the banks of the lake, several lake terraces record Pleistocene variations of the lake levels. In the terraces, the lake deposits are often interbedded with pyroclastites emitted by the volcanoes located on the northern side of the lake. Our research focuses on the southwestern part of the lake, where several pyroclastites interbedded with lake deposits allow establishing a regional tephrostratigraphy, which is being Ar/Ar dated. In this area, the study of the pyroclastites allows to understand the impact of volcanism on the palaeohydrography: all the valleys where filled-in with pyroclastites which induced heavy disruptions of the drainage network. Moreover, our research enlightens evidences that volcanic activity was responsible for the enclosure of the lake and that the major transgression of the lake, dated ca. 100 ka, is not only linked to changes in the water balance, but at first linked to volcanic activity.; Situé en Anatolie orientale, le lac de Van est le quatrième lac fermé du monde par son volume et sa superficie. Sur son pourtour, de nombreuses terrasses témoignent des variations de son niveau au cours du Pléistocène. La partie nord du lac de Van est constituée d'une série de volcans quaternaires ayant émis des pyroclastites dont certaines sont interstratifiées avec ces dépôts lacustres. La présente étude porte sur la partie sud-ouest du lac où l'étude des produits volcaniques en relation stratigraphique avec les dépôts lacustres permet d'établir une téphrostratigraphie régionale dont le calage chronologique (Ar/Ar) est en cours. Deux ignimbrites successives ont rempli et fossilisé les paléo-vallées, désorganisant totalement le réseau hydrographique régional et séparant progres-sivement le bassin versant du lac de Van de celui du Tigre. Finalement, l'activité volcanique semble à la fois responsable du caractère endoréique du lac de Van et de la transgression majeure du lac, datée de ca. 100 ka. Celle-ci ne serait pas seulement une réponse à des variations du bilan hydrique mais correspondrait d'abord à un forçage d'origine volcanique.
Published: 2010
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45. Formation of the Upper Pleistocene terraces of Lake Van (Turkey)

Author: Aurélien Christol, Stéphane Scaillet, Catherine Kuzucuoğlu, Hervé Guillou, Monique Fort, Jean-Louis Reyss, Michel Fontugne, Damase Mouralis, Daniel Brunstein, Ebru Akköprü, Halil Zorer, Ali-Fuat Doğu, Mustafa Karabıyıkoğlu, Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Identités et Différenciation de l'Environnement des Espaces et des Sociétés (IDEES), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Institut de Recherche Interdisciplinaire Homme et Société (IRIHS), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochrononologie Traceurs Archéométrie (GEOTRAC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Van, Paléocéanographie (PALEOCEAN), Océan et Interfaces (OCEANIS), Identité et Différenciation de l’Espace, de l’Environnement et des Sociétés (IDEES), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire Homme et Société (IRIHS), Normandie Université (NU), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire Homme et Société (IRIHS), and Normandie Université (NU)-Université de Caen Normandie (UNICAEN)
Subjects: 010506 paleontology, terraces, Pleistocene, [SDE.MCG]Environmental Sciences/Global Changes, Pyroclastic rock, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Arts and Humanities (miscellaneous), Paleoclimatology, Earth and Planetary Sciences (miscellaneous), volcanic activity, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Geomorphology, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Lake Van, [SHS.GEO]Humanities and Social Sciences/Geography, Upper Pleistocene, climate change, Volcano, Terrace (geology), 13. Climate action, Facies, Geology, Chronology, Marine transgression
Abstract: Sedimentological and geomorphological studies of terraces around Lake Van (1647 m) provided a preliminary framework for lake-level variations. The elevations of terraces and past lake level were measured with a differential global positioning system. A chronology is developed using 234 U/ 230 Th dating of travertines, 39 Ar/ 40 Ar dating of pyroclastites and 14 C dating of organic matter. Facies and stratigraphic correlations identify four transgressions (C1 0 ,C 1 00 ,C 2 0 and C2 00 ), each followed by a regression which ended with low lake levels that caused river incision and terrace formation. Evidence of the oldest transgression (C1 0 ) is found in the uppermost reaches of valleys up to 1755 m, an altitude higher than the present lake threshold (1736 m). This C1 0 transgression may be related to pyroclastic flows which dammed an outlet located in the western part of the lake basin and which is dated to before 105 ka. After 100 ka, a second transgression (C1 00 ) reached 1730/1735 m, possibly related to a younger ignimbrite flow, in association with high water inflow (warm and/or wetter conditions). The two younger transgressions reached 1700-1705 m. The first one (C2 0 ) is dated to 26- 24.5 cal. ka BP and the second one (C2 00 ) to 21-20 cal. ka BP. Available data suggest that the long-term lake-level changes responded mainly to climate oscillations. Additional events such as river captures caused by volcanic falls filling valleys, tectonism, erosion and karstic diversion may have impacted these long-term lake-level changes. Copyright # 2010 John Wiley & Sons, Ltd.
Published: 2010
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46. Origin and geodynamic evolution of late Cenozoic potassium-rich volcanism in the Isparta area, southwestern Turkey

Author: Catherine Deniel, Stéphane Scaillet, Bernard Platevoet, Kirsten Drüppel, André Poisson, Jacques-Marie Bardintzeff, Nevzat Özgür, Kamil Yılmaz, Ömer Elitok, Yildirim Dilek, Wolfgang Siebel, Muharrem Satir, Hervé Guillou, Suleyman Demiref University, Technical University of Berlin / Technische Universität Berlin (TU), Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Technische Universität Berlin (TU), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Basalt, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lava, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, Trachyte, Pyroclastic rock, Lava dome, Geology, 010502 geochemistry & geophysics, 01 natural sciences, Volcanic rock, 13. Climate action, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Phenocryst, Mafic, Petrology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Post-collisional potassic-rich volcanism of Golcuk Volcano in the Isparta area of southwestern Turkey consists of two groups: (i) extracaldera lavas, corresponding mainly to Pliocene activity; and (ii) intracaldera lavas and pyroclastics (ignimbrite flows and ash/pumice fall deposits) formed during the Quaternary. Extracaldera volcanic rocks mainly comprise lamprophyre (minette), basaltic trachyandesite, trachyandesite, and trachyte. A close relationship exists between the silica content and phenocryst type in the extracaldera volcanics such that trachyte-trachyandesites with SiO2 57wt% and basaltic trachyandesites are characterized mainly by mafic phenocryst phases (e.g. pyroxene, amphibole, biotite-phlogopite). These features suggest suppression of plagioclase crystallization under high H2O pressure conditions. Intracaldera volcanics are composed of tephriphonolitic dikes, remnants of lava flows and domes at the caldera rim, and a trachytic lava dome on the caldera floor. The Golcuk flows and pyroclastics are mainly characterized by strong incompatible element enrichment in large ion lithophile elements (LILEs; e.g. Cs, Ba, U, and Th) relative to K, Rb, and high-field strength elements (e.g. Nb, Ta, and Ti). We conclude that the Golcuk lavas were derived from a metasomatized lithospheric mantle source containing phlogopite-amphibole garnet peridotite; the latter resulted from metasomatism by a hydrous fluid phase related to subducted sediments and oceanic crust. The parental magma for the extracaldera volcanics was lamprophyric, and that for the intracaldera volcanics was basanitic. All the geological and geochemical data show that the alkaline Golcuk lavas display a gradual decrease in silica content with decreasing eruption age, indicating that, in the Isparta volcanic province, the asthenospheric melt component became more important over time. In the extracaldera volcanics, 87Sr/86Sr isotope ratios of the evolved trachyte-trachyandesites range between 0.70366 and 0.70504, whereas these ratios are lower in the less evolved basaltic trachyandesite and lamprophyres, varying in narrow ranges around 0.70365 and between 0.70374 and 0.70453, respectively. The 143Nd/144Nd values lie between 0.51264 and 0.51273 in trachyandesites, 0.51267 and 0.51273 in basaltic trachyandesites, and 0.51270 and 0.51274 in lamprophyres. In the intracaldera lavas, the 87Sr/86Sr isotope ratio is 0.70361 in the tephriphonolite and 0.70388 in the intracaldera trachytic lava dome. The 143Nd/144Nd isotope ratio is 0.51274 in the analysed tephriphonolitic flow and 0.51271 in the intracaldera trachytic lava dome; these values are higher than that of trachyte-trachyandesites of the extracaldera volcanics. The Sr-Pb isotopic signatures indicate that crustal contamination was significant for the evolved extracaldera volcanics, but was negligible for the intracaldera volcanics. The epsilon Nd values of the Golcuk volcanics range between 0 and 2.0. The low Sr isotope ratios and positive epsilon Nd values are characteristic features of a depleted mantle source. The isotopically depleted and incompatible enriched nature of the Golcuk lavas point to recent enrichment processes prior to partial melting of the mantle source. Conversely, their radiogenic lead isotope compositions (206Pb/204Pb=19.19-19.54, 207Pb/204Pb=15.64-15.67, 208Pb/204Pb=39.12-39.49) indicate an enriched mantle source region.
Published: 2010
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47. Preservation by basalt of a staircase of latest Pliocene terraces of the River Murat in eastern Turkey: Evidence for rapid uplift of the eastern Anatolian Plateau

Author: Rob Westaway, Stéphane Scaillet, Tuncer Demir, Ali Seyrek, Hervé Guillou, David R. Bridgland, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Basalt, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, Plateau, 010504 meteorology & atmospheric sciences, Continental crust, Geochemistry, Holocene climatic optimum, Fluvial, Crust, 15. Life on land, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, 13. Climate action, Tributary, Erosion, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geomorphology, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Unspiked K–Ar dating makes the age of the Cakmakozu basalt in eastern Turkey 1818 ± 39 ka (± 2σ). This basalt overlies a staircase of four terraces of the River Murat, a Euphrates tributary, each separated vertically by ∼ 20 m. We deduce from the relationship with the basalt that these fluvial deposits aggraded during successive ∼ 40 ka climate cycles around the Pliocene–Pleistocene boundary (probably MIS 72-66). The incision and rock uplift at ∼ 0.5 mm a− 1, thus indicated, are roughly consistent with the ∼ 500 m of entrenchment of this ∼ 1.8 Ma Murat palaeo-valley into a former lake basin since the Mid-Pliocene climatic optimum. We infer that the ∼ 130 m of incision in this locality since ∼ 1.8 Ma dramatically underestimates the associated rock uplift, estimated as ∼ 600 m. The ∼ 1100 m of rock uplift and ∼ 800 m of surface uplift thus estimated since the Mid-Pliocene indicate (assuming Airy isostatic equilibrium) ∼ 5 km of thickening of the continental crust, from ∼ 37 km to the present 42 km. Eastern Anatolia was thus at a much lower altitude in the Mid-Pliocene than at present, consistent with the low-relief lacustrine palaeo-environment. We infer that the subsequent development of topography and excess crustal thickness are being caused by coupling between surface processes and induced flow in the lower crust: climate change following the Mid-Pliocene climatic optimum resulted in faster erosion that has drawn mobile lower crust beneath the study region.
Published: 2009
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48. Late Cenozoic surface uplift, basaltic volcanism, and incision by the River Tigris around Diyarbakır, SE Turkey

Author: Tuncer Demir, Stéphane Scaillet, Hervé Guillou, Anthony Beck, David R. Bridgland, Ali Seyrek, Rob Westaway, Faculty of Mathematics and Computing (UK), School of Civil Engineering and Geosciences [Newcastle], Newcastle University [Newcastle], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Department of Soil Science, Harran University, Department of Geography, Harran University, Durham University, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Basalt, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Underplating, 010504 meteorology & atmospheric sciences, Pleistocene, Turkey, Diyarbakır, Fluvial, Incision, Crust, Late Miocene, 010502 geochemistry & geophysics, 01 natural sciences, Uplift, Paleontology, 13. Climate action, Tigris, General Earth and Planetary Sciences, Mafic, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, 0105 earth and related environmental sciences, Terrane
Abstract: We document the staircase of terraces of the River Tigris in the Diyarbakir area of SE Turkey, in the northern Arabian Platform, and improve control on the ages of these terrace deposits by dating of overlying basalt flows using the unspiked K–Ar technique. These fluvial terraces are formed of polymict gravel, including clasts derived from the Anatolian metamorphic terrane farther north as well as of local basalt. At least 9 Tigris terraces have been recognised so far, the highest of which, ∼200 m above present river level, marks the local transition from stacked deposition to fluvial incision, the timing of which is bounded between the mid Late Miocene and the Middle Pliocene. Our K–Ar dating indicates a hiatus in fluvial incision in the late Early Pleistocene, as basalts dated to 1.22 ± 0.02 and 1.07 ± 0.03 Ma overlie Tigris gravels at very similar levels, ∼60–70 m above the present river. The lower terraces record the subsequent entrenchment of the modern Tigris valley following an increase in incision rates in the early Middle Pleistocene, evident from the disposition of younger basalt, dated to 0.43 ± 0.02 Ma, capping fluvial gravel only ∼21–22 m above the present river level. Numerical modelling can account for the observed uplift history, as the response to coupling between surface processes and induced flow in the lower crust, with the mobile lower-crust thin (∼5–7 km thick), consistent with the known presence of a thick layer of mafic underplating at the base of the crust beneath the Arabian Platform.
Published: 2009
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49. Miocene magmatism and tectonics of the easternmost sector of the Calama-Olacapato-El Toro fault system in Central Andes at ∼24°S: Insights into the evolution of the Eastern Cordillera

Author: Natalia Hauser, Roberto Mazzuoli, R Omarini, Anna Gioncada, Stéphane Scaillet, Valerio Acocella, A. Uttini, Luigina Vezzoli, Hervé Guillou, A Dini, M. Matteini, Dipartimento di Scienze della Terra [Pisa], University of Pisa - Università di Pisa, Dipartimento di Scienze Chimiche ed Ambientali, Universitá degli Studi dell’Insubria, Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Dipartimento di Scienze Geologiche [Roma TRE], Università degli Studi Roma Tre, University of Brasilia [Brazil] (UnB), CNR Istituto di Geoscienze e Georisorse [Pisa] (IGG-CNR), Consiglio Nazionale delle Ricerche (CNR), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Universitá degli Studi dell’Insubria = University of Insubria [Varese] (Uninsubria), Università degli Studi Roma Tre = Roma Tre University (ROMA TRE), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Eastern Cordillera, 010504 meteorology & atmospheric sciences, CENTRAL ANDES, Geochemistry, geochronology, Central Andes, structural geology, 010502 geochemistry & geophysics, 01 natural sciences, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Basaltic andesite, Geología, volcanic stratigraphy, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 0105 earth and related environmental sciences, EASTERN CORDILLERA, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, Fractional crystallization (geology), Volcanic arc, BACKARC MAGMATISM, Continental crust, GEOCHRONOLOGY, Geology, Crust, 15. Life on land, Volcanic rock, Laccolith, backarc magmatism, Magmatism, VOLCANIC STRATIGRAPHY, STRUCTURAL GEOLOGY, CIENCIAS NATURALES Y EXACTAS
Abstract: The Miocene Las Burras - Almagro - El Toro magmatic complex lies ∼300 km to the east of the Central Andes volcanic arc, in the easternmost sector of the transverse Calama - Olacapato - El Toro fault zone. The magmatic rocks of the Las Burras - Almagro - El Toro complex comprise a monzogabbro to monzogranite laccolith like intrusion and basaltic andesite to dacite volcanic rocks that include sevenlithostratigraphic members. New Rb-Sr dates indicate that the intrusive rocks are ca. 14 Ma, and K-Ar dates suggest emplacement ages of ca. 12.8-6.4 Ma for the volcanic rocks. The emplacement of the intrusion was controlled by N-S - striking strike-slip faults in a context of oblique convergence; the volcanism, which occurred along WNW-ESE - and N-S - striking extensional faults, relates to the Calama - Olacapato - El Toro fault zone. Two magmatic phases were recognized. Intrusive and volcanic rocks of the older magmatic phase (ca. 14-13 Ma) are characterized by Ba/Nb (7-14), La/Ta (11-18), and isotopic ratios (87Sr/86Sr: 0.704339-0.705281, 143Nd/144Nd: 0.512713-0.512598), which are intraplate characteristics. The source of the older magmas was isotopically depleted lithospheric mantle rich in K, Rb, and Th. Energy constrained-assimilation and fractional crystallization (EC-AFC) modeling indicates that fractional crystallization and crustal assimilation moderately modified magma composition during its residence in the crust. The products of the younger magmatic phase (ca. 11-6 Ma) have higher Ba/Nb (24-42) and La/Ta (24-30) and 87Sr/86Sr (0.706738-0.708729) and lower 143Nd/144Nd (0.512433-0.512360). The results of EC-AFC modeling exclude a significant role for the upper crust in the generation of the most primitive magmas of this phase. Their compositions can be explained by (1) contamination of the primary magmas having originated in a depleted mantle with a mafic crust, or (2) the contribution of isotopically enriched mantle zones. Shallow differentiation and moderate contamination by continental crust can explain the composition of the intermediate and evolved products of the younger phase. The variation of the magma source characteristics at 11 Ma is discussed in the frame of the complex geo-dynamical setting in this region. Fil: Mazzuoli, R.. Università degli Studi di Pisa; Italia Fil: Vezzoli, L.. Università Degli Studi Dell'insubria; Italia Fil: Omarini, Ricardo Hector. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Acocella, V.. Università Degli Studi Roma Tre; Italia Fil: Gioncada, A.. Università degli Studi di Pisa; Italia Fil: Matteini, Massimo. Universidade do Brasília; Brasil Fil: Dini, A.. Istituto Di Geoscienze E Georisorse, Sezione Di Pisa; Italia Fil: Guillou, H.. Centre National de la Recherche Scientifique. Laboratoire des Sciences du Climat et de l'Environnement ; Francia Fil: Hauser, Natalia. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Uttini, A.. Università Degli Studi Dell'insubria; Italia Fil: Scaillet, S.. Centre National de la Recherche Scientifique. Laboratoire des Sciences du Climat et de l'Environnement ; Francia
Published: 2008
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50. Fluvial dissection, isostatic uplift, and geomorphological evolution of volcanic islands (Gran Canaria, Canary Islands, Spain)

Author: Moises Martín-Betancor, Pablo G. Silva, Stéphane Scaillet, Francisco-Jose Perez-Torrado, Inmaculada Menéndez, Hervé Guillou, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lava, Fluvial, 010502 geochemistry & geophysics, Neogene, 01 natural sciences, Tectonic uplift, Volcano, 14. Life underwater, Ravine, Quaternary, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geomorphology, Geology, Sea level, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: Digital analysis of torrential gullies (‘barrancos’) deeply incised into the volcanic Island of Gran Canaria (Canary Islands) allows us to extract the longitudinal profiles and pre-incision surfaces for individual basins, from which morphometric parameters (length, elevation, area, slope) have been calculated. Other derived parameters, such as ridgeline profiles, maximum incision values, volume removed by fluvial erosion, geophysical relief and isostatic uplift, have also been computed. Based on K/Ar ages for the island, well-constrained incision-uplift rates have been calculated by means of the combination of different methodological approaches commonly used in orogens and large mountain ranges. The geomorphological and morphometric analyses reveal that the island is clearly divided into four environmental quadrants determined by the combination of a couple of key-factors: the age of the volcanic surfaces and the climatic conditions. These factors determine a young sector covered with Plio-Quaternary platform-forming lavas (finished at 1.9–1.5 Ma) evolving under contrasting wet (NE) to dry (SE) climates, and an older sector, conserving the residual surfaces of the Miocene shield building (14.5–8.7 Ma) at the ridgelines, also subjected to wet (NW) and dry (SW) climates. Incision is related to the age zonation of the island. Maximum incisions (
Published: 2008
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