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1. Lu-Hf Isotopic Data of the Mbé-Sassa-Mbersi Tonalite (Central Cameroon Domain): Indicator of ca. 1.0 Ga Juvenile Tonian Magmatism in the Region

Author

Olivier Vanderhaeghe, Emmanuel Negue Nomo, Aurélien Eglinger, Armin Zeh, Periclex Martial Fosso Tchunte, Pierre Barbey, Rigobert Tchameni, and Alliance Nicaise Saha-Fouotsa

Subjects
Rift, Outcrop, Tonian, Magmatism, Geochemistry, Shear zone, Brasiliano orogeny, Geology, Zircon
Abstract

The Pan-African/Brasiliano orogenic belts are a part of numerous Neoproterozoic orogenic belts that belong to the long-lived orgenic cycle that distancing phase started at the Tonian around 1.0 Ga. The Tonian magmatism fairly documented in the Neoproterozoic belts of Borborema Province (NE-Brazil), seemed so far inexistent in the Central African Orogenic Belt (CAOB) although these two belts were geologically correlated. Through the Lu-Hf geochronological analysis on zircon of tonalite, the present work, coupled with the previous data, suggests the existence of a Tonian age magmatism in the Central Cameroon Domain of the CAOB although the latter is much reworked. The Nguesseck tonalite outcrops in the northern part of the Mbe-Sassa-Mbersi region, in the northern edge of Central Cameroon Domain of the CAOB and in the Tchollire-Banyo shear zone (TBSZ). The Lu-Hf data obtain on the zircon grains of this tonalite reveal juvenile HfTDM age of ca. 1.0 Ga. This age, combined to the previous geochemical data suggests that the protholites of this tonalite would have extracted from the source during the distancing phase (rifting and oceanization) of the Pan-african/Brasiliano orogeny at the early Neoproterozoic.

Published
2021
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2. Cordierite-Bearing Orbicules Record Bulk Assimilation and the Pulsating Nature of Magma Ascent: The Lafaye Orbicular Granite (France)

Author

Michel Grandprat, François Faure, and Pierre Barbey

Subjects
Geophysics, Bearing (mechanical), Geochemistry and Petrology, law, Magma, engineering, Geochemistry, Cordierite, Assimilation (biology), engineering.material, Orbicular granite, Geology, law.invention
Abstract

The Lafaye orbicular body was emplaced in the Villatange tonalite-granodiorite unit of the Guéret magmatic complex (Massif Central, France). It consists of plagioclasic orbicules (4–35 cm diameter) embedded in homogeneous cordierite granodiorite. Orbicule cores consist mostly of residual metasedimentary xenoliths or autolithic plagioclasic cumulates. Rims (0.7–8 cm thickness) are single- or multi-layered; layers, mostly comb-textured, comprise alternating sheets dominated by cordierite (XFe = 0.32–0.37) or plagioclase (mostly An25–30). Additional mineral phases are minor biotite (XFe = 0.52; AlVI = 0.58–0.92 atoms per formula unit) and interstitial quartz. Plagioclase and cordierite morphologies (needle-like, skeletal, branching or fan-shaped) indicate growth under high initial supersaturation. However, the final polyhedral shapes and primary zoning of many individual plagioclase crystals, as well as evidence of partial recrystallization, imply significant textural maturation. Whole-rock major and trace element data (A/CNK = 1.12–1.46) and Sr and Nd isotopic compositions (εNd(355 Ma) = −8.6 to −7.4; 87Sr/86Sr(355 Ma) = 0.7110–0.7147) suggest that the parental magma of the orbicules resulted from bulk assimilation of aluminous metasediments by a Villatange-type granodioritic magma. Heterogeneous nucleation and growth of plagioclase and cordierite around xenoliths/autoliths are interpreted in terms of (1) adiabatic decompression of magma pulses ascending in dykes leading to superheating and resorption of early solids, and (2) volatile exsolution, inducing undercooling, supersaturation, and rim crystallization. The variability of layers (number, thickness, mineral distribution, and texture) is considered to result from oscillatory crystallization combined with variable plagioclase growth rates linked to changes in the degree of supersaturation as a function of the extent of melt degassing, itself linked to magma transfer dynamics.

Published
2021
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3. When nuclear medicine radiological protection meets biological COVID-19 protection

Author

Denis Agostini, Jonathan Vigne, Catherine Nganoa, Nicolas Aide, Damien Peyronnet, Pierre Barbey, Service de médecine nucléaire [CHU Caen], Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-CHU Caen, Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Tumorothèque de Caen Basse-Normandie (TCBN), Service de Pharmacie [CHU Caen], CHU Caen, Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN), Physiopathologie et imagerie des troubles neurologiques (PhIND), Normandie Université (NU)-Normandie Université (NU)-Institut National de la Santé et de la Recherche Médicale (INSERM), GIP Cyceron (Cyceron), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CHU Caen, Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Tumorothèque de Caen Basse-Normandie (TCBN)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche interdisciplinaire pour la prévention et le traitement des cancers (ANTICIPE), Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Tumorothèque de Caen Basse-Normandie (TCBN)-Centre Régional de Lutte contre le Cancer François Baclesse [Caen] (UNICANCER/CRLC), UNICANCER-Tumorothèque de Caen Basse-Normandie (TCBN)-Normandie Université (NU)-UNICANCER-Institut National de la Santé et de la Recherche Médicale (INSERM), Installations de Mise en Oeuvre et de GEstion des Radioéléments [Caen] (IMOGERE), Normandie Université (NU)-Normandie Université (NU), Normandie Université (NU)-UNICANCER-Tumorothèque de Caen Basse-Normandie (TCBN)-UNICANCER-Institut National de la Santé et de la Recherche Médicale (INSERM), and Bodescot, Myriam

Subjects
2019-20 coronavirus outbreak, Coronavirus disease 2019 (COVID-19), Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), [SDV.IB.MN]Life Sciences [q-bio]/Bioengineering/Nuclear medicine, 030204 cardiovascular system & hematology, [SDV.IB.MN] Life Sciences [q-bio]/Bioengineering/Nuclear medicine, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, medicine, Radiology, Nuclear Medicine and imaging, ComputingMilieux_MISCELLANEOUS, [SDV.MP.VIR] Life Sciences [q-bio]/Microbiology and Parasitology/Virology, [SDV.MHEP.ME] Life Sciences [q-bio]/Human health and pathology/Emerging diseases, [SDV.MHEP.ME]Life Sciences [q-bio]/Human health and pathology/Emerging diseases, business.industry, General Medicine, medicine.disease, 3. Good health, Radiology Nuclear Medicine and imaging, Radiological weapon, [SDV.MP.VIR]Life Sciences [q-bio]/Microbiology and Parasitology/Virology, Medical emergency, Radiation protection, business, Coronavirus Infections
Abstract

International audience

Published
2020
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4. Geochemistry and Sm–Nd isotopic composition of the Imiter Pan-African granitoids (Saghro massif, eastern Anti-Atlas, Morocco): Geotectonic implications

Author

Abdelkhalek Alansari, Said Ilmen, Abderrahmane Soulaimani, Bouchra Baidada, Pierre Barbey, Moha Ikenne, Brian Cousens, Université Cadi Ayyad [Marrakech] (UCA), Department of Earth Sciences [Ottawa], Carleton University, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie Appliquée et Géo-Environnement (LAGAGE), Faculté des Sciences Agadir (FSA), and Université Ibn Zohr [Agadir]-Université Ibn Zohr [Agadir]

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Pan african, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Crust, Massif, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Isotopic composition, Craton, West african, [SDU]Sciences of the Universe [physics], Primitive mantle, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

The Imiter inlier (eastern part of the Moroccan Anti-Atlas) is located on the northwestern border of the West African Craton (WAC) and exhibits a range of Pan-African granitoids. Three massifs that crosscut the Imiter Saghro Group were targeted in this work: the Igoudrane granodiorite, Bou Teglimt granodiorite and Bou Fliou granite. We present here additional geochemical analyses (major and trace elements) and Sm-Nd isotopic data, which define two distinct groups: (i) the Igoudrane massif (677 Ma) and (ii) the Bou Teglimt granodiorite (576 Ma) and the Bou Fliou granite (550 Ma). Geochemical data confirm the calc-alkaline signature of the studied granitoids. Both groups of granitoids are slightly peraluminous and show strong negative anomalies in Nb, Ta and Ti in multi-element plots normalized to the primitive mantle. The granitoids have low 143 Nd/ 144 Nd initial ratios (0.5116–0.5117), with T DM model ages ranging from 1.73 to 1.52Ga. The eNd (t) values are negative, decreasing from the Igoudrane samples (−1.1 to −3.1) to the Bou Teglimt granodiorite (−3.0 to −3.3) and Bou Fliou (−4.2 to −4.8). All these data suggest a mixed magmatic origin involving a juvenile mantle source and an old, at least Paleoproterozoic crust. Given Mesoproterozoic rocks are lacking or very scarce in the Anti-Atlas, these results confirm the existence of an old cratonic basement beneath the eastern Anti-Atlas, and therefore suggest that the northern border of the West African Craton must be placed further to the north, as suggested by previous work in this region.

Published
2017
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5. Impact du nucléaire sur la santé et l’environnement en situation non accidentelle

Author

Claude Stéphan and Pierre Barbey

Subjects
General Medicine
Abstract

Quel est l’impact du fonctionnement d’une centrale nucléaire sur l’environnement, les terres et les populations avoisinantes ? Quelles sont les phases industrielles de la filière, de l’extraction du minerai à l’exploitation des centrales, qui comportent les effets sensibles les plus controversés ? Deux chercheurs répondent à nos questions en exprimant des points de vue opposés.

Published
2018
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6. Skeletal quartz and dendritic biotite: Witnesses of primary disequilibrium growth textures in an alkali-feldspar granite

Author

Karine Pistre, Jean-Louis Paquette, Pierre Barbey, Jean-Paul Gremilliet, François Faure, Cyrille Delangle, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Terrae Genesis, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
Undercooling, 010504 meteorology & atmospheric sciences, Granite, Geochemistry, Geology, Cordierite, engineering.material, Poikilitic, 010502 geochemistry & geophysics, Dendritic growth, 01 natural sciences, law.invention, Albite, Geochemistry and Petrology, law, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, engineering, Plagioclase, Texture, Crystallization, Alkali feldspar, Quartz, Biotite, 0105 earth and related environmental sciences
Abstract

International audience; We describe a case of S-type alkali-feldspar granite (quartz/K-feldspar/plagioclase/ biotite/garnet ∼ 30/35/20/13/2 vol%) showing skeletal and dendritic textures. It consists of three nested units distinguishable by the size of biotite crystals: a first-emplaced unit characterized by small biotite flakes (0.4–9 mm); a second unit with cm-sized biotite platelets (0.3–28 mm) outlining a syn-magmatic foliation; and a third unit formed of large biotite plates (0.7–850 mm) showing dendritic and radial growth patterns.Quartz occurs mostly as rounded to euhedral grains, but also shows complex shapes (serrated outline, re-entrants, etc.). Cathodoluminescence imaging reveals that grains consist of both rounded and skeletal bluish cores (quartz-1) rimmed by reddish overgrowths (quartz-2) that lead locally to the coalescence of neighbouring grains and equilibrated texture. Biotite is poikilitic enclosing dominantly quartz grains but also in lesser amount plagioclase and garnet. In the third unit, biotite shows textures typical of dendritic growth (bifurcating, radiating or branching structures, skeletal core). Plagioclase (An≤25) occurs as small euhedral to subhedral grains scattered in the matrix or forming glomerophyric aggregates. K-feldspar (Or74–100) mostly forms an almost equilibrated mosaic of anhedral perthitic crystals; it also appears in association with albite as a secondary phase replacing plagioclase. The crystallization sequence started with garnet, then proceeded with quartz, plagioclase, biotite and K-feldspar, ended with cordierite, and was followed by subsolidus reequilibration.The variability in size and morphology of quartz and biotite is interpreted in terms of variable undercooling depending on temperature of the host-rocks and on more or less intense degassing of magma batches with variable melt water content. Here, rapid crystallization prevented significant textural reequilibration and allowed the initial crystallization textures of quartz to be preserved. Overall, this study shows that behind the common “coarse-grained” texture of quartz in granite, subsist primary disequilibrium crystallization textures.

Published
2019
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7. Transfer of yttrium-90 to breast milk during radiosynoviorthesis of the knee joint

Author

Denis Agostini, Damien Peyronnet, Gilbert Pigrée, Séverine Cruet-Hennequart, Christian Marcelli, Pierre Barbey, Jonathan Vigne, Johann Cesini, Installations de Mise en Oeuvre et de GEstion des Radioéléments [Caen] (IMOGERE), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Service de Rhumatologie [CHU Caen], Normandie Université (NU)-Normandie Université (NU)-CHU Caen, Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Tumorothèque de Caen Basse-Normandie (TCBN), Service de médecine nucléaire [CHU Caen], Mobilités : Vieillissement, Pathologie, Santé (COMETE), Normandie Université (NU)-Normandie Université (NU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Service de Médecine Nucléaire [Paris 18eme], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-AP-HP - Hôpital Bichat - Claude Bernard [Paris], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Caen Normandie (UNICAEN), Groupe coeur et ischémie, CHU Caen, Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Centre de Recherches Pétrographiques et Géochimiques (CRPG), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
030203 arthritis & rheumatology, medicine.medical_specialty, business.industry, [SDV]Life Sciences [q-bio], [SCCO.NEUR]Cognitive science/Neuroscience, chemistry.chemical_element, [SHS.PSY]Humanities and Social Sciences/Psychology, General Medicine, Yttrium, Knee Joint, Breast milk, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, chemistry, Orthopedic surgery, medicine, Radiology, Nuclear Medicine and imaging, Radiology, business, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019
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8. The geologic record of the exhumed root of the Central African Orogenic Belt in the central Cameroon domain (Mbé – Sassa-Mbersi region)

Author

Rigobert Tchameni, Aurélien Eglinger, Pierre Barbey, Periclex Martial Fosso Tchunte, Alliance Nicaise Saha-Fouotsa, Armin Zeh, Olivier Vanderhaeghe, Emmanuel Negue Nomo, Département des Sciences de la Terre [Univ Ngaoundéré] (UN-FS), Faculté de Sciences [Univ Ngaoundéré] (UN-FS), Université de Ngaoundéré/University of Ngaoundéré [Cameroun] (UN)-Université de Ngaoundéré/University of Ngaoundéré [Cameroun] (UN), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Karlsruher Institut für Technologie (KIT), University of Yaoundé [Cameroun], Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Felsic, 010504 meteorology & atmospheric sciences, Metamorphic rock, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, 010502 geochemistry & geophysics, 01 natural sciences, [SDU]Sciences of the Universe [physics], Mafic, Shear zone, Protolith, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Mylonite, Zircon, Gneiss
Abstract

We present structural, petrological, geochemical and geochronological data compiled in a new geological map on the high-grade metamorphic rocks exposed in the Mbe – Sassa-Mbersi region located along the Tchollire-Banyo Shear Zone, at the northern edge of the Central Cameroon domain. The region exposes a complex assemblage of metabasic (hornblendite, metagabbro, amphibolite) and metasedimentary (garnet paragneiss, calc-silicate gneiss) rocks alternating with ubiquitous migmatitic intermediate to felsic gneisses. U-Pb ages on detrital zircon in paragneiss point to the contribution of Archean, Paleoproterozoic and Neoproterozoic sources, and suggest a maximum deposition age of 725 ± 12 Ma for their sedimentary protolith. The protolith of some amphibolites was emplaced during the Neoproterozoic as indicated by U–Pb ages on magmatic zircon at 600 ± 4 and 599 ± 6 Ma. Plutonic rocks with I-type chemical signatures were emplaced discontinuously over a period of ca. 80 Ma. The magmatic evolution started with the intrusion of magnesian medium-K tonalites and trondhjemites at 651 ± 3 Ma, followed by magnesian high-K hornblende-biotite granites and ferroan shoshonitic biotite granites until 599 ± 2 Ma. Finally, pegmatite dykes were emplaced along dextral shear zones at 573 ± 2 Ma. The metamorphic rocks show a penetrative shallow-dipping foliation partially to totally transposed in a NE–SW trending steep-dipping foliation bearing a shallow-dipping lineation. These ductile syn-migmatitic fabrics, developed under high-grade metamorphic conditions in the presence of melt, between the metamorphic peak at ca. 1.3 GPa–770 °C, and the following isothermal decompression down to ca. 0.8 GPa. In situ U–Pb dating of metamorphic zircon rims from a garnet migmatitic paragneiss yields an age of 582 ± 4 Ma. Localization of high-grade deformation is indicated by the development of the Tchollire-Banyo Shear Zone, characterized by mutually crosscutting subvertical and shallow-dipping mylonitic to ultramylonitic shear zones associated with sinistral and top-to-the SW kinematic criteria, respectively. These data indicate that the Central Cameroon domain exposed in the Mbe – Sassa-Mbersi region, represents the exhumed mid-to lower part of the former orogenic root of the Pan-African Central Africa Orogenic Belt that has undergone partial melting, lateral flow and intrusion of mafic to felsic calc-alkaline magmas between 650 and 580 Ma. The waning stage of the Pan-African orogeny is marked by the emplacement of syntectonic pegmatitic granite at ca. 575 Ma in subvertical E-W trending retrogressive dextral shear zones.

Published
2019
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9. SHRIMP U–Pb zircon geochronology of the granitoids of the Imiter Inlier: Constraints on the Pan-African events in the Saghro massif, Anti-Atlas (Morocco)

Author

Abdelkhalek Alansari, Moha Ikenne, Pierre Barbey, Brian Cousens, Bouchra Baidada, Said Ilmen, Faouziya Haissen, Abderrahmane Soulaimani, Université Cadi Ayyad [Marrakech] (UCA), Laboratoire de Géologie Appliquée et Géo-Environnement (LAGAGE), Faculté des Sciences Agadir (FSA), Université Ibn Zohr [Agadir]-Université Ibn Zohr [Agadir], Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [Ottawa], Carleton University, Université Hassan II [Casablanca] (UH2MC), and Managem Group

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Subduction, Proterozoic, Archean, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Context (language use), Massif, 010502 geochemistry & geophysics, 01 natural sciences, Craton, 13. Climate action, [SDU]Sciences of the Universe [physics], Geochronology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Zircon
Abstract

This study presents new U–Pb zircon ages for three granitoid bodies in the Imiter inlier at the eastern part of the Moroccan Anti-Atlas chain, which is located in the northwestern edge of the West African Craton (WAC). Analyzes of zircon grains yield the following ages: 538 ± 6 and 575 ± 10 Ma for the Igoudrane massif , 567 ± 6 Ma for the nearby Bou Teglimt granodiorite , and 582 ± 6 Ma for the Bou Fliou granite . These new data reveal that the Igoudrane massif is younger than previously thought (677 Ma), and that all the granitoids in the Imiter area are Ediacaran in age and are related to the Ouarzazate Group. Sm-Nd isotopic data yield negative eNd(t) values (−4.5 to −0.2) and T DM model ages of 1.04–1.82 Ga. These data indicate the presence of an inherited Paleoproterozoic to Archaean component in some zircon grains and show that generation of the parent magmas involved a Neoproterozoic juvenile contribution and recycling of an older crustal component. These new data allow reinterpreting the geochemical and isotopic data of the granitoids, and revisiting the structural significance to the Igoudrane massif, which was assumed until now to be coeval with the major Pan-African event of the Central Anti-Atlas. They also bring significant constraints to discuss the context and age of deposition of the Saghro Group, which is still a matter of debate. All these data provide evidence of an emplacement of the Imiter granitoids in a subduction complex, which affected all of the Anti-Atlas chain during the Late Proterozoic time.

Published
2019
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10. Palladium-Mediated Site-Selective C–H Radio-iodination

Author

Alain Manrique, Victor Babin, Emmanuelle Dubost, Frédéric Fabis, Céline Chollet, Jean-Philippe Bouillon, Alexandra Hébert, Thomas Cailly, Grégory Pieters, Florian Benoist, Pierre Barbey, Centre d'Etudes et de Recherche sur le Médicament de Normandie (CERMN), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Normandie Université (NU), Service de Chimie Bio-Organique et de Marquage (SCBM), Médicaments et Technologies pour la Santé (MTS), Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Chimie Organique et Bioorganique : Réactivité et Analyse (COBRA), Institut de Chimie Organique Fine (IRCOF), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut Normand de Chimie Moléculaire Médicinale et Macromoléculaire (INC3M), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Signalisation, électrophysiologie et imagerie des lésions d’ischémie-reperfusion myocardique (SEILIRM), Institut Normand de Chimie Moléculaire Médicinale et Macromoléculaire (INC3M), Institut de Chimie du CNRS (INC)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie Organique Fine (IRCOF), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Primary (chemistry), 010405 organic chemistry, Organic Chemistry, Halogenation, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, Biochemistry, Medicinal chemistry, 0104 chemical sciences, chemistry.chemical_compound, chemistry, Sodium iodide, Site selective, Physical and Theoretical Chemistry, [CHIM.RADIO]Chemical Sciences/Radiochemistry, Palladium
Abstract

International audience; The palladium-mediated C–H radio-iodination of arenes using sodium iodide as the primary isotopic source is reported and performed without chemical know-how in 30 min and applied to the synthesis of complex radio-iodinated compounds of biological interest.

Published
2018
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11. Reply to comment by Ngako and Njonfang on 'The Adamawa-Yade domain, a piece of Archaean crust in the Neoproterozoic Central African Orogenic belt (Bafia area, Cameroon)', by Jacqueline Tchakounté et al., Precambrian Research 299 (2017) 210–229

Author

Charles Nkoumbou, Joseph Mvondo-Ondoa, Armin Zeh, J. Penaye, Martin de Wit, Sadrak Félix Toteu, Jacqueline Numbem Tchakounté, Pierre Barbey, Aurélien Eglinger, Université de Yaoundé I, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), 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), United Nations Educational, Scientific and Cultural Organization (UNESCO), Karlsruhe Institute of Technology (KIT), Centre for Geological and Mining research, Nelson Mandela Metropolitan University [Port Elizabeth, South Africa], Centre de Recherches Pétrographiques et Géochimiques (CRPG), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Archean, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Crust, Geodynamics, 010502 geochemistry & geophysics, 01 natural sciences, Domain (software engineering), Precambrian, Paleontology, Craton, Strain pattern, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

V. Ngako and E. Njonfang addressed in their comment an interesting and debated issue about the collision geodynamics of the Pan-African Central African Orogenic Belt (CAOB) in Cameroon. However, the reason for this comment is still not clear to us since it mainly deals with issues far away from the scope of our study, namely, the pre-collisional set up of the belt. The comment raises two main points – the reworking process during plate collision and the Pan-African strain pattern – not discussed in our paper for the simple reason that it was not our goal and because our data set does not even allow such discussion. Having said that, the comment gives us the opportunity to clarify our view on the nature of the Adamawa-Yade domain (Central Cameroon) and the early evolution of the CAOB. We will successively discuss two other points raised in the comment: (1) our Fig. 12 depicting a possible pre-collisional configuration at the northern and southern margin of the Congo craton in the Early Neoproterozoic, and (2) the nature and extent of the Adamawa-Yade domain.

Published
2018
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12. The Marbat metamorphic core-complex (Southern Arabian Peninsula): Reassessment of the evolution of a Neoproterozoic island-arc from petrological, geochemical and U-Pb zircon data

Author

Julien Berger, Jean-Louis Paquette, Damien Roques, Jérôme Ganne, Pierre Barbey, Yoann Denèle, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
010504 meteorology & atmospheric sciences, Oman, Pluton, Geochemistry, Metamorphism, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Geochemistry and Petrology, Metamorphic facies, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Underplating, Metamorphic core complex, Geology, Arabian-Nubian shield, Tectonic underplating, 13. Climate action, [SDU]Sciences of the Universe [physics], Tonian, Neoproterozoic, Protolith, Zircon, Zircon U-Pb
Abstract

The Marbat basement (Sultanate of Oman) belongs to the Neoproterozoic accretion domain of the Arabian-Nubian shield. We present new geochronological, petrological and geochemical data as an extension of our previous study (Denele et al., 2017) re-interpreting this basement as a metamorphic core complex (MCC). We showed that this MCC consists of a metamorphic unit (Juffa complex) separated by an extensional detachment from a plutonic unit (Sadh complex and Tonalite plutons). Geochemical data show that the Juffa metasediments correspond to volcanogenic graywackes, suggesting deposition in front of a juvenile magmatic arc. New in situ U-Pb zircon data show that the protolith of the Juffa paragneisses is Tonian in age (960-830 Ma). The Juffa complex recrystallized under amphibolite facies conditions (950 MPa, 630 degrees C) corresponding to thermal gradient of 17-18 degrees C/km, i.e. close to that observed in fore-arc environment subjected to tectonic underplating. It was then retrogressed (< 400 MPa, < 400 degrees C) during exhumation of the MCC. Phase assemblages of the Sadh complex and Tonalite plutons record magmatic temperatures estimated at 700-840 degrees C and 610-840 degrees C from hornblende and zircon-saturation thermometry, respectively; pressures are grossly estimated at ca. 250 MPa. These data and structural evidence led us to consider that the Sadh complex is a plutonic unit emplaced during exhumation of the MCC. Hence, we re-interpret the previously published zircon core U-Pb ages of the Banded gneisses (ca. 860-830 Ma) as inherited, and zircon rim ages (ca. 815 Ma) as the age of their intrusion. This suggests that the parent magma of all these granitoids could have interacted with volcanic material equivalent to the Juffa complex. Overall, the Marbat area developed during the Tonian and involved (i) deposition of volcanosediments (Juffa complex) in an island-arc environment (960-830 Ma); (ii) metamorphism under middle pressure conditions during tectonic underplating at ca. 820-815 Ma, followed by emplacement of plutonic rocks in the upper crust during initiation of the MCC at ca. 815-810 Ma; and (iii) late-tectonic intrusions associated with MCC amplification at ca. 800-790 Ma (Mahall intrusives and Tonalite plutons).

Published
2018
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13. Reply to comment by M. Bouyo on 'The Adamawa–Yade domain, a piece of Archaean crust in the Neoproterozoic Central African Orogenic belt (Bafia area, Cameroon)', by Jacqueline Tchakounté et al., Precambrian Research 299 (2017) 210–229

Author

Jacqueline Tchakounté, Aurélien Eglinger, Sadrak Félix Toteu, Armin Zeh, Charles Nkoumbou, Joseph Mvondo-Ondoa, Joseph Penaye, Martin de Wit, Pierre Barbey, Université de Yaoundé I, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), 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), United Nations Educational, Scientific and Cultural Organization (UNESCO), Karlsruhe Institute of Technology (KIT), Centre for Geological and Mining research, Nelson Mandela Metropolitan University [Port Elizabeth, South Africa], Centre de Recherches Pétrographiques et Géochimiques (CRPG), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, 010502 geochemistry & geophysics, 01 natural sciences, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience

Published
2018
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14. The Adamawa-Yadé domain, a piece of Archaean crust in the Neoproterozoic Central African Orogenic belt (Bafia area, Cameroon)

Author

Pierre Barbey, J. Penaye, Joseph Mvondo-Ondoa, Charles Nkoumbou, Martin de Wit, Aurélien Eglinger, Jacqueline Numbem Tchakounté, S.F. Toteu, Armin Zeh, Université de Yaoundé I, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), 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), United Nations Educational, Scientific and Cultural Organization (UNESCO), Karlsruher Institut für Technologie (KIT), Centre for Geological and Mining research, Nelson Mandela Metropolitan University [Port Elizabeth, South Africa], Centre de Recherches Pétrographiques et Géochimiques (CRPG), and Université de Lorraine (UL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Continental crust, Archean, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Crust, Orogeny, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Gondwana, Craton, Continental margin, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], Petrology, Protolith, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

New field observations, ages and geochemical data are presented for the Adamawa-Yade domain, forming part of Central African Orogenic Belt in Cameroon. This belt delineates the northern margin of the Congo craton and is part of the Braziliano/Pan-African orogenic system, which was formed during amalgamation of the West Gondwana continent at the end of the Neoproterozoic. U–Pb dating indicates that the protoliths of some orthogneisses from the Adamawa-Yade domain were emplaced during three distinct periods. Tonalite-Trondhjemite-Granodiorite (TTG) suites in the Makenene area intruded at ca. 3.0–2.5 Ga, and were affected by partial melting at ca. 2.08–2.07 Ga, during the Eburnean orogeny, and by a magmatic event with a metamorphic overprint at 0.64–0.61 Ga, during the Pan-African orogeny. A dioritic orthogneiss from the Maham area, north of Makenene, was emplaced at 2.07 Ga and also reworked at 0.62–0.61 Ga. The youngest granitic orthogneisses, sampled in the vicinity of Bafia, Bep and Ngaa-Bape, yield intrusion ages of 0.64–0.63 Ga. Some of these Neoproterozoic plutonic rocks show shoshonitic affinity and reveal eNd (630 Ma) values ranging from −1.2 to −6.9 (1.7 > T DM > 1.1 Ga), and 87 Sr/ 86 Sr initial ratios of 0.706 and 0.704, providing evidence for crustal reworking during the Pan-African collision. The isotopic geochemical characteristics provide evidence that potassic magmas result from the interaction between the Archaean TTG continental crust and magmas derived from a mantle enriched in silica and incompatible elements during subduction underneath a continental margin. The Bafia group appears as a complex geological entity comprised of an Archaean/Palaeoproterozoic basement and its Neoproterozoic sedimentary cover, both deformed and recrystallized at ca. 0.61 Ga. The crustal evolution of the Adamawa-Yade domain is very similar to that inferred for the northern margin of the Congo craton (the Ntem complex and Nyong series). This and the sedimentary record suggest that the Adamawa-Yade domain represents an Archaean/Palaeoproterozoic microcontinent, which was detached from the northern margin of the Congo craton in the early Neoproterozoic, but became re-accreted together with the Mayo Kebbi (magmatic) arc during the Pan-African orogeny.

Published
2017
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15. Strike-slip metamorphic core complexes: Gneiss domes emplaced in releasing bends

Author

Damien Roques, Pierre Barbey, Yoann Denèle, Jérôme Ganne, Dominique Chardon, Sonia Rousse, Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre de Recherches Pétrographiques et Géochimiques (CRPG), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Metamorphic core complex, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, 010502 geochemistry & geophysics, Strike-slip tectonics, 01 natural sciences, [SDU]Sciences of the Universe [physics], Petrology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Gneiss
Abstract

We investigate the development of a Neoproterozoic metamorphic core complex (MCC) in the Marbat area (southern Arabian Peninsula). The MCC is a gneiss dome emplaced in a releasing bend along a dextral strike-slip fault system. Dome emplacement-related extension was at a high angle to the long axis of the dome and 65 degrees from the strike-slip fault system. Shortening is recorded in the upper plate of the MCC in a direction normal to the extension direction. Extensional emplacement of the gneiss dome accommodated lower crust exhumation and contributed to the formation of a ductile strike-slip releasing bend from an initial fault step. The Marbat example allows defining transversal stretching-dominated strike-slip MCCs, which would represent the early development stages of longitudinal stretching-dominated strike-slip MCCs. Conversely, longitudinal stretching-dominated strike-slip MCCs produced at low finite extension would result from strike-slip-dominated transtension. This study bears important implications for lower crust exhumation under pulla-part basin systems in obliquely convergent or divergent settings.

Published
2017
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16. Structure and LA-ICP-MS zircon U–Pb dating of syntectonic plutons emplaced in the Pan-African Banyo-Tcholliré shear zone (central north Cameroon)

Author

Léontine Tekoum, Periclex Martial Fosso Tchunte, Aurélien Eglinger, Emmanuel Negue Nomo, Nicaise Alliance Saha Fouotsa, Fenguye Sun, Pierre Barbey, Rigobert Tchameni, Olivier Vanderhaeghe, Université de Yaoundé I, Université de Lorraine (UL), Université de Ngaoundéré/University of Ngaoundéré [Cameroun] (UN), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Jilin University (JLU), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Université de Lorraine (UL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), GeoRessources, and Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
geography, Felsic, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Pluton, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Massif, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Transpression, Leucogranite, Shear (geology), [SDU]Sciences of the Universe [physics], Shear zone, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Zircon
Abstract

The Tchollire massif, in central north Cameroon, consists of elongated granite plutons that crop out along the Pan-African Tchollire-Banyo shear zone (TBSZ), a potential suture zone within the Central Africa Orogenic Belt. New structural and geochronological data on these granites constrain the tectonic regime and timing of the TBSZ. The plutons consist of syntectonic granites and granodiorite containing dioritic mafic enclaves. They show an S2 sub-vertical foliation, that trends NE-SW to ENE-WSW. The related L2 lineation is subhorizontal to shallowly plunging to the SW or NE. Kinematic indicators such as asymmetric folds, sigmoidal-shape boudins, shear bands, imbricated feldspar phenocrysts along antithetic fractures point to a sinistral sense of shear. Microstructural analysis shows that structures are acquired from the submagmatic to the low temperature solid state suggesting progressive deformation of the magma during its emplacement, crystallization and cooling. U-Pb zircon dating on this massif yields emplacement ages of 719 ± 12 Ma for the biotite-amphibole granite and muscovite granite, 652.2 ± 5.4 Ma for the biotite-granite and 632 ± 13 Ma for the leucogranite. These geochronological data show in addition, Palaeoproterozoic inherited ages of 1631 ± 30 Ma on the leucogranites of this massif, and point to a Palaeoproterozoic contribution in their genesis. The range of ages (ca. 87 Ma) points to the timing of syntectonic emplacement of felsic magmas coeval with sinistral transpression along the TBSZ during the Pan-African orogeny. These results show that the TBSZ has recorded prolonged deformation associated with crustal magmatism between the Palaeoproterozoic Adamawa-Yade domain to the southeast and the Sinassi-Mayo Kebbi Neoproterozoic magmatic arc to the Northwest.

Published
2017
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17. Boris Choubert: Unrecognized visionary geologist, pioneer of the global tectonics

Author

Philippe Le Vigouroux, Anne-Marie Boullier, Dominik Letsch, Umberto G. Cordani, Benito Ábalos, Brian Upton, Jacques Kornprobst, Åke Johansson, Pierre Barbey, Roy H. Gabrielsen, Jean-Pierre Burg, José Ignacio Gil-Ibarguchi, David Corrigan, Stefan Claesson, Ramon Capdevila, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre (ISTerre), 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-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Swedish Museum of Natural History (NRM), Universidade de São Paulo = University of São Paulo (USP), Geological Survey of Canada [Ottawa] (GSC Central & Northern Canada), Geological Survey of Canada - Office (GSC), Natural Resources Canada (NRCan)-Natural Resources Canada (NRCan), Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Comité français d'histoire de la géologie (COFRHIGEO), Centre François Viète : épistémologie, histoire des sciences et des techniques - EA1161 (CFV), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Université de Brest (UBO)-Université de Nantes - UFR Lettres et Langages (UFRLL), Université de Nantes (UN)-Université de Nantes (UN), Grant Institute, University of Edinburgh, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), 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), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Universidade de São Paulo (USP), Université de Nantes (UN)-Université de Brest (UBO), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Université de Lorraine (UL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans ( LMV ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université Jean Monnet [Saint-Étienne] ( UJM ) -Institut de Recherche pour le Développement et la société-Université Clermont Auvergne ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de Recherches Pétrographiques et Géochimiques ( CRPG ), Université de Lorraine ( UL ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des Sciences de la Terre ( ISTerre ), 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 Grenoble Alpes ( UGA ), Eidgenössische Technische Hochschule [Zürich] ( ETH Zürich ), Géosciences Rennes ( GR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique ( CNRS ), Swedish Museum of Natural History, Stockholm, Department of Geosciences, University of Oslo ( UiO ), Comité français d'histoire de la géologie ( COFRHIGEO ), Centre François Viète : épistémologie, histoire des sciences et des techniques, and Université de Nantes ( UN ) -Université de Brest ( UBO )

Subjects
Pangaea, PRÉ-CAMBRIANO, 010504 meteorology & atmospheric sciences, Paleozoic, 010502 geochemistry & geophysics, 01 natural sciences, tectonique des plaques, [SHS.HISPHILSO]Humanities and Social Sciences/History, Philosophy and Sociology of Sciences, Precambrian, Paleontology, dérive continentale, orogeny, ComputingMilieux_MISCELLANEOUS, [ SDU.STU.PE ] Sciences of the Universe [physics]/Earth Sciences/Petrography, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Wegener, lcsh:QE1-996.5, Précambrien, Geology, Orogeny, orogenèse, lcsh:Geology, Plate tectonics, Tectonics, Continental drift, Palaeozoic belts, Dérive continentale, Tectonique des plaques, Orogenèse, 13. Climate action, plate tectonics, continental drift, Geologist
Abstract

This work is a review of Boris Choubert’s paper (1935), which was published in French under the rather devalorizing title: “Research on the Genesis of Palaeozoic and Precambrian Belts.” Despite its innovative content, this article had no impact either at the time of its publication or even later. It begins with the construction of a remarkable fit of the circum-Atlantic continents. This was based on the −1.000 meters isobath instead of the shoreline. Thirty years before Bullard et al. (1965), it demonstrated in an indisputable way the reality of the continents motion on the surface of the Earth. Therefore, Choubert designated Wegener’s “continental drift” as the main cause of tectonics. Even going beyond Wegener’s theory, he argued that this mechanism was efficient well before the formation of the Triassic Pangæa, during the whole Palaeozoic to result in the building of the Caledonian and Hercynian mountains. Although he was still encumbered by the vocabulary of the time regarding geosynclines, Boris Choubert described tectonics based on the horizontal mobility of the Precambrian continental blocks. Oddly enough, he did not apply this model to the Precambrian structures, which he attributed to the effects of the Earth’s rotation on the continental crust during its solidification. At the time of its publication, this paper was a very important step towards understanding global tectonics. Unfortunately, Choubert’s contemporaries did not generally recognize its significance. Ce travail est une analyse de l’article de Boris Choubert (1935) paru en français sous le titre un peu réducteur: « Recherches sur la genèse des chaînes paléozoïques et antécambriennes. » Malgré son contenu novateur, cet article n’a eu aucun retentissement à l’époque de sa publication, ni même plus tard. Il débute par la construction d’un remarquable assemblage des continents péri-atlantiques fondé sur l’isobathe −1.000 mètres et non pas sur la ligne de rivage. Trente ans avant Bullard et al. (1965), il démontre de façon indiscutable la réalité du déplacement des masses continentales à la surface de la Terre. Dès lors, Choubert privilégie totalement la « dérive des continents » comme moteur de la tectonique. Allant au-delà même de la vision de Wegener, il fait jouer ce mécanisme bien avant la formation de la Pangée triasique, pendant toute la durée de l’ère primaire, au cours de l’érection des chaînes calédonienne et hercynienne. Bien que restant prisonnier du vocabulaire de l’époque sur les géosynclinaux, Boris Choubert décrit une tectonique fondée sur la mobilité des blocs continentaux précambriens. Curieusement, il n’applique pas ce modèle aux déformations précambriennes qu’il attribue aux effets de la rotation de la Terre sur une croûte continentale en voie de solidification. Lors de sa parution, cet article représentait un pas très important vers la compréhension de la tectonique globale et il est regrettable qu’il n’ait pas été mieux reçu par ses contemporains. ISSN:0037-9409 ISSN:1777-5817

Published
2018
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18. Timing of granite emplacement, crustal flow and gneiss dome formation in the Variscan segment of the Pyrenees

Author

Yoann Denèle, Bernard Laumonier, Jean-Louis Paquette, Philippe Olivier, Gérard Gleizes, Pierre Barbey, Yoann Denèle, Bernard Laumonier, Jean-Louis Paquette, Philippe Olivier, Gérard Gleizes, and Pierre Barbey

Abstract

The Variscan segment of the Pyrenees is well suited to study the timing of crustal-scale deformations as crustal flow and gneiss dome formation. This has been constrained from a synthesis of available structural and geochronological data of intrusive rocks, as well as new zircon U–Pb age determinations via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). After a stage of moderate thickening by fold–thrust belt development in the upper crust between 323 and 308 Ma, the Variscan segment of the Pyrenees experienced crustal flow at c. 306 Ma and then gneiss dome formation at c. 304 Ma. Localization of the deformation along reverse-dextral shear zones occurred at c. 300 Ma. The Variscan segment of the Pyrenees recorded a high-temperature regime, which allowed crustal flow of the middle crust, but with limited amounts of heat which induced rapid cooling. The development of this enigmatic orogenic segment of the Variscan belt is closely contemporaneous with the formation of the Cantabrian Orocline and could correspond to a lithospheric-scale shear zone that accommodated buckling of the orocline. Late Variscan lithospheric delamination and asthenospheric upwelling associated with buckling in the core of the Cantabrian Orocline could explain the short-period high-temperature regime in the Variscan segment of the Pyrenees.

Published
2016
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