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The 350 km-long Adjara-Trialeti fold-and-thrust belt of southwestern Georgia is the result of the structural inversion of a continental back-arc basin developed in the Paleogene on the upper (Eurasian) plate of the northward subducting northern branch of the Neotethys. Low-temperature thermochronological data [fission-track and (U-Th)/He analyses on apatite] from sedimentary and plutonic rocks provide robust constraints on the tectonic evolution of the Adjara-Trialeti orogenic belt. Fission-track central ages range from the Middle Eocene to the Middle Miocene (46–15 Ma); helium ages are clustered in the Late Miocene-Pliocene (10–3 Ma). Time-temperature paths obtained integrating thermochronologic, stratigraphic, and radiometric data show that the volcanosedimentary basin fill of the Adjara-Trialeti back-arc basin underwent progressive burial heating prior to final cooling/exhumation in the late Middle Miocene-Pliocene. These new data show that the Adjara-Trialeti back-arc basin was inverted and developed as a fold-and-thrust belt starting at 14–10 Ma, in tune with widespread Middle-to-Late Miocene shortening and exhumation across wide areas of the Middle East, from the eastern Pontides of NE Turkey to the Lesser Caucasus in northern Armenia and NW Azerbaijan, and the Talysh and Alborz ranges in northern Iran. Such a supraregional tectonism is interpreted as a far-field effect of the Arabia-Eurasia collision along the Bitlis suture ca. 400 km to the south of the study area.

Raman spectral shifts of carbonaceous materials arising from faulted rocks produce varied and complex results. By analyzing faulted and adjacent non-faulted samples from three discrete localities in France, Italy, and Morocco, we assess changes in specific Raman parameters, including G-peak width, G-peak position, and peak intensity ratios. We consistently observe a shift in Raman parameters between faulted and non-faulted samples; however, the direction and magnitude of this shift varies. Raman peak intensity ratios are shown to both increase and decrease on fault planes. The majority of samples exhibit decreasing peak width and peak position in the faulted samples, but this is not consistent; in two samples an increase is observed, but the shift tends to be small. These data are compared to published Raman spectral shifts from experimental fault data. Our results suggest that fault zone deformation processes may measurably change the carbon nanostructure in faulted rocks. The inconsistent nature of Raman spectral shifts in the fault rock samples analyzed, and those published suggest that a complex set of factors control carbon nanostructure changes in fault rocks. These factors, although not discriminated here, likely include, background temperature, frictional heating, strain, carbonaceous material type, amongst others. We have shown that Raman Spectral shifts occur in faulted rocks with implications for how Raman data are used to predict maximum temperatures in faulted sedimentary rocks. We recognize the potential for a range of fault zone processes to modify Raman spectral shifts, however, systematic sampling across individual fault zones is critical.

International audience; Thirteen seismic reflection profiles and field observations have been used to build a three-dimensional watertight geological model of the sub-surface architecture of the Trapanese carbonate platform unit of the Apennine-Maghrebian chain in the Mt. Kumeta and Mt. Rocca Busambra (NW Sicily, Italy). Either a single step or a two-step thrust-fault deformation model is acceptable on the basis of seismic interpretation but the integration of 3D model reconstruction and 3D geomechanical restoration, validates only the scenario with a single stage of deformation.The 3D model highlights along strike variations of the structural style for the Trapanese unit where pre-existing discontinuities (e.g. inherited Mesozoic normal faults) played an important role in the preferential occurrence of hinterland verging structures. In detail, backthrusts (N-verging) are dissected by tear faults along the Mt. Kumeta structure whereas an imbricate backthrust system evolves into thrust along the Mt. Rocca Busambra structure. Shortening estimate indicates low amount of internal deformation affecting the carbonate platform unit (

Young back-arc rift basins, because of the not yet dissipated extensional thermal signature, can be easily inverted following changes in the geodynamic regime and/or far-field stress transmission. Structural inversion of such basins mainly develops through reactivation of normal faults, particularly if the latter are favourably oriented with respect to the direction of stress transfer. The Adjara-Trialeti fold-and-thrust belt of SW Georgia is an example of this mechanism, resulting from the structural inversion of a continental back-arc rift basin developed on the upper plate of the northern Neotethys slab in Paleogene times, behind the Pontides-Lesser Caucasus magmatic arc. New low-temperature thermochronological data [apatite fission-track (AFT) and (U-Th)/He (AHe) analyses] were obtained from a number of samples, collected across the Adjara-Trialeti belt from the former sedimentary fill of the basin and from syn-rift plutons. AFT central ages range between 46 and 15 Ma, while AHe ages cluster mainly between 10 and 3 Ma. Thermal modelling, integrating AFT and AHe data with independent geological constraints (e.g. depositional/intrusion age, other geochronological data, thermal maturity indicators and stratigraphic relationships), clearly indicates that the Adjara-Trialeti back-arc basin was inverted starting from the late Middle Miocene, at 14-10 Ma. This result is corroborated by many independent geological evidences, found for example in the adjacent Rioni, Kartli and Kura foreland basins and in the eastern Black Sea offshore, which all suggest a Middle-Late Miocene phase of deformation linked with the Adjara-Trialeti FTB building. Adjara-Trialeti structural inversion can be associated with the widespread Middle-to-Late Miocene phase of shortening and exhumation that is recognised from the eastern Pontides to the Lesser Caucasus, the Talysh and the Alborz ranges. This tectonic phase can in turn be interpreted as a far-field effect of the Arabia-Eurasia collision, developed along the Bitlis suture hundreds of kilometres to the south.

Thermal history reconstructions can help to better characterise the geological history of areas that experienced a polyphase tectonic evolution. The integration of published stratigraphic/structural data with new and pre-existing data on thermal maturity (clay mineralogy, Raman spectroscopy, vitrinite reflectance, and pyrolysis) of both surface and subsurface sedimentary successions of a wide region of Georgia including -north to south- the southern Greater Caucasus, the western Kura Basin, and the Adjara-Trialeti fold-and-thrust belt (FTB) provides cogent constraints on its late Mesozoic-Cenozoic tectono-sedimentary evolution. Overall, thermal maturity spans from the low diagenesis (60–80 °C) in the Upper Miocene section of the Kura Basin to anchizone-epizone (about 400 °C) in the central Greater Caucasus axial zone. In more detail, different maturity trends and thermal histories point to the existence of two domains formed by positive tectonic inversion: (i) the Adjara-Trialeti FTB from an Eocene rift basin and (ii) the Greater Caucasus from a Mesozoic rift basin. Multiple thermal indicators, along with stratigraphic/structural evidence, show that the Paleocene section of the Adjara-Trialeti basin fill reached the upper oil window (ca. 115 °C) during maximum sedimentary burial and that the whole basin was then exhumed starting from the late Middle Miocene. A positive correlation between thermal maturity and stratigraphic age points to a limited thermal effect of tectonic loading. In the southern Greater Caucasus, thermal maturity increases progressively with stratigraphic age, from ca. 100 °C (Upper Eocene) to 400 °C (Lower Jurassic), in broad agreement with the reconstructed thickness of the basin-fill succession, thus indicating that most of the thermal maturity was again induced by sedimentary burial. As to the flexural western Kura Basin, its Maikopian (Oligocene-Early Miocene) section reached the oil window (up to ca. 110 °C) whereas the Middle-Late Miocene one is immature. The Kakheti ridge -a highly tectonised portion of the Kura Basin- reached immature to early mature conditions.

Temperature-dependent clay minerals and vitrinite reflectance data, surface and subsurface geological constraints were used to unravel the burial evolution of the Ordovician-Quaternary sedimentary successions from the inner to the outer zones of the Zagros fold-and-thrust belt in the Fars province (Iran). These sedimentary successions were buried to their thermal maxima during early to late diagenesis, achieving temperatures corresponding to the immature to early mature stages of hydrocarbon generation. They experienced low levels of thermal maturity in the Interior Fars, corresponding to vitrinite reflectance values between 0.38 and 0.66%, to mixed layers illite-smectite (I-S) with an illite content between 30 and 75% and to KI values between 0.97 and 1.18°Δ2θ. In the Central and Coastal Fars, vitrinite reflectance ranges between 0.35 and 0.51%, the illite content in I-S displays values between 20 and 85% and KI data are between 0.71 and 1.30°Δ2θ. In individual anticlines, mixed layers I-S show an increase of the illite content as a function of stratigraphic age (depth), suggesting that levels of thermal maturity are controlled by sedimentary burial. One dimensional thermal history models allowed us: (i) to estimate the maximum burial experienced by the sedimentary successions and the amount of the sedimentary pile currently removed by erosion, (ii) to determine the thickness of the ophiolite units obducted during Late Cretaceous time in the High Zagros, and (iii) to define the onset of oil generation for the Albian source rocks throughout the Zagros belt. Paoleothermal data were used to constrain the geometry of eroded structures in a 253 km long cross-section extending from the High Zagros to the Coastal Fars. Along the cross-section, lithostatic load slightly decreases towards the foreland (e.g., from 3.65 km to 3.2 km for the Bangestan Group) and the amount of the eroded material varies between ∼6 km (above anticlines in the Central and Interior Fars) and ∼200 m (above synclines in the external part of the belt).

The recent 10th–11th of July 2015 Volcan de Colima eruption involved the collapse of the summit dome that breached to the south generating pyroclastic density currents (PDCs) along the Montegrande ravine on the southern flank of the volcano. Trees within the valley were buried, uprooted and variably transported by the PDCs, while the trees on the edges of the valley and on the overbanks, were mainly burned and folded. The emplacement temperature of valley confined and overbank PDC deposits were reconstructed using Partial Thermal Remanent Magnetization (pTRM) analysis of lithic clasts and Charcoal Reflectance analysis (Ro %) applied to the charred wood. A total of 13 sites were sampled for the pTRM study and 39 charcoaled wood fragments were collected for the charcoal optical analysis along the entire deposit length in order to detect temperature variation from proximal to distal zone. The result overlap from both data sets display a T max from ≃345°–385 °C in valley-confined area (from 3.5 to 8.5 km from the vent) and ≃170°–220 °C (from 8.0 to 10.5 km from the vent) in unconfined distal area. The emplacement temperature pattern along the 10.5 km long deposit appears related to the degree of topography confinement: valley confined and unconfined. In particular the valley confined setting is very conservative in terms of temperature, while the major drop occurs in a very narrow space where the PDC expanded over unconfined flat topography just at the exit of the main valley. This study represents the first attempt in determining the relationship between PDCs flow dynamics variation and topographic confining using deposit emplacement temperature as key proxy.

In this paper we reply to the criticisms advanced by Narkiewicz (2017) on the paper by Schito et al. (2017). We clarify the issues related to the stratigraphic and thermal maturity constraints used for reconstructing burial and thermal models of the two blocks of the Holy Cross Mountains. We also show how geological evidences brought by Narkiewicz (2017) as a proof of elevated Variscan heat flow are not conclusive or at least suggest the occurence of a localized thermal anomaly only along the area of the Holy Cross Fault. In the end, we performed new burial and thermal models in the Kielce region demonstrating that stratigraphic thickness variations between Schito et al. (2017) and Narkiewicz et al. (2010) produce only negligible differences in levels of thermal maturity of Paleozoic rocks. In addition, we outline that levels of thermal maturity for Silurian rocks can be matched only by using constant heat flow values through the Paleozoic and point to a decisive role for the absence of regional high Variscan heat flow in the area.

The stretching of continental lithosphere results in asthenospheric upwelling, raising of isotherms, melting during decompression and eventually seafloor spreading. The thermal maturity of overlying sedimentary organic matter from these settings would be expected to be distinctly altered by these processes, however this is still poorly constrained and quantitatively unexplored. International Ocean Discovery Program (IODP) Expeditions 367–368 cored sediments at the Continent Ocean Transition (COT) on the Northern Margin of the South China Sea (SCS). From two settings at the South East China COT we measured and modelled thermal maturity in pre-/syn- to post-rift sediments making use of a range of thermal maturity parameters. Various heat-flow evolutionary scenarios were investigated, with notable jumps in thermal maturity for sediments corresponding to different depositional packages. In order to match observations of thermal maturity, it was found that the deeper and likely pre-rift sediments were heated to temperatures as high as 200 °C during initial breakup. Achieving this temperature for the deeper sediments requires that significant additional heat be imparted at shallow depths (e.g. exposure to at least the far-field effects of a magmatic intrusion or subsurface expressions of volcanism). The post-rift sediments have lower thermal maturities which are likely due to limited burial and the absence of late post-rift magmatism. The comparison of the SE China COT with other margin examples highlights some parameters controlling the thermal evolution and its record.

Paleo-thermometers in sedimentary basins often drive to misleading thermal modelling when applied alone or only on potentially productive Paleozoic source rocks. Different paleo-thermal and thermo-chronological data have been used as constraints to model the Silurian to Cenozoic succession of a recently drilled well in the onshore portion of the Baltic Basin, in northern Poland. This dataset provides an integrated platform for thermal maturity assessment contributing to the highly debated reconstruction of the thermal history of the Baltic Basin in the last decade. The well stratigraphy consists of a Lower Paleozoic marine clayey and arenaceous/calcareous succession, about 1000 m thick that is unconformably overlain by a 2000 m thick Permian to Cenozoic sequence, developed in a continental to shallow marine environment. Optical microscopy, FT-IR and Raman spectroscopy analysis of organic matter have been coupled with (U–Th)/He data to produce a robust vitrinite reflectance profile and constrain the 1D thermal modelling of the well. In addition, such a thermal maturity profile was validated by an independent thermal modelling calibrated by the smectite illitization kinetics. Both models identify high heat flow conditions (up to 1.7 HFU) at the end of Mesozoic. The Lower Paleozoic succession entered the late oil window of HC generation during this last heating event.

Thermal maturity of six organic rich samples from Jurassic continental successions cropping out in the Holy Cross Mountains in Central Poland, has been characterized by classic thermal maturity indicators, micro-Raman spectroscopy and Palynomorph Darkness Index, in order to create a multi-method workflow for complex palynofacies thermal maturity assessment. Transmitted light observations on dispersed organic matter define a Hettangian lacustrine depositional environment, characterized by periods of reducing/oxidizing conditions and variable sedimentation rates. Thermal maturity detected by classical maturity indicators and PDI indicates an early maturation stage of hydrocarbon generation and is in agreement with spectroscopic analyses performed on phytoclast groups. Moreover, Raman parameters in the sporomorph group indicate a systematic shift toward a lower degree of aromatization compared to the phytoclast group. Finally, the multivariate statistical analysis performed on Raman spectra is found to be a promising tool to define and predict the heterogeneity of dispersed organic matter in sediments.

Pyroclastic density currents (PDCs) can have devastating impacts on urban settlements, due to their dynamic pressure and high temperatures. Our degree of understanding of the interplay between these hot currents and the affected infrastructures is thus fundamental not only to implement our strategies for risk reduction, but also to better understand PDC dynamics. We studied the temperature of emplacement of PDC deposits that destroyed and buried the Villa dei Papiri, an aristocratic Roman edifice located just outside the Herculaneum city, during the AD79 plinian eruption of Mt Vesuvius (Italy) by using the thermal remanent magnetization of embedded lithic clasts. The PDC deposits around and inside the Villa show substantial internal thermal disequilibrium. In areas affected by convective mixing with surface water or with collapsed walls, temperatures average at around 270 °C (min 190 °C, max 300 °C). Where the deposits show no evidence of mixing with external material, the temperature is much higher, averaging at 350 °C (min 300 °C; max 440 °C). Numerical simulations and comparison with temperatures retrieved at the very same sites from the reflectance of charcoal fragments indicate that such thermal disequilibrium can be maintained inside the PDC deposit for time-scales well over 24 hours, i.e. the acquisition time of deposit temperatures for common proxies. We reconstructed in detail the history of the progressive destruction and burial of Villa dei Papiri and infer that the rather homogeneous highest deposit temperatures (average 350 °C) were carried by the ash-sized fraction in thermal equilibrium with the fluid phase of the incoming PDCs. These temperatures can be lowered on short time- (less than hours) and length-scales (meters to tens of meters) only where convective mixing with external materials or fluids occurs. By contrast, where the Villa walls remained standing the thermal exchange was only conductive and very slow, i.e. negligible at 50 cm distance from contact after 24 hours. We then argue that the state of conservation of materials buried by PDC deposits largely depends on the style of the thermal interactions. Here we also suggest that PDC deposit temperatures are excellent proxies for the temperatures of basal parts of PDCs close to their depositional boundary layer. This general conclusion stresses the importance of mapping of deposit temperatures for the understanding of thermal processes associated with PDC flow dynamics and during their interaction with the affected environment.

Understanding the thermal behavior of pyroclastic density currents (PDCs) is crucial for forecasting impact scenarios for exposed populations as it affects their lethality and destructiveness. Here we report the emplacement temperatures of PDC deposits produced during the paroxysmal explosive eruption of Merapi (Central Java) on 5 November 2010 based on the reflectance of entombed charcoal fragments. This event was anomalously explosive for Merapi, and destroyed the summit dome that had been rapidly growing, with partial collapses and associated PDCs, since October 26. Results show mean reflectance values mainly between 0.17 and 0.41. These new data provide a minimum temperature of the flow of 240–320 °C, consistent with previous estimations determined from independent field, engineering, and medical observations published in the literature for this eruption. A few charcoal fragments recorded higher values, suggestive of temperatures up to 450 °C, and we suggest that this is due to the thermal disequilibrium of the deposits, with larger block-size clasts being much hotter than the surrounding ash matrix. Charring temperatures show no major differences between proximal and distal PDC deposits and are significantly lower than those that may be associated with a fast growing dome dominated by dense and vitric non-vesicular rocks. We therefore infer that the decrease in temperature from that at fragmentation (>900 °C) occurred in the very initial part of the current

Anisotropy of magnetic susceptibility (AMS) has been applied to the study of shallow fault zones, although interpretation of the results requires establishing clear relationships between petrofabric and magnetic features, magnetic behaviour of fault rocks, and an extensive knowledge of P-T conditions. In this work, we demonstrate that magnetic methods can be applied to the study of heterogeneous fault zones, provided that a series of requisites are met. A major fault zone within the Iberian plate (Daroca thrust), showing transpressional movements during Cenozoic time was chosen for this purpose, because of the exceptional outcrops of fault gouge and microbreccia and its relevance within the context of the northeastern Iberian Plate. Magnetic fabrics were analysed and the results were compared with foliation and S-C structures measured within the fault zone. Clay mineral assemblages suggest maximum burial depths shallower than 2 km (

Mixed layer clay minerals, vitrinite reflectance and geochemical data from Rock-Eval pyrolysis were used to constrain the burial evolution of the Mesozoic–Cenozoic successions exposed at the Kuh-e-Asmari (Dezful Embayment) and Sim anticlines (Fars province) in the Zagros fold-and-thrust belt. In both areas, Late Cretaceous to Pliocene rocks, show low levels of thermal maturity in the immature stages of hydrocarbon generation and early diagenetic conditions (R0 I–S and Ro% values < 0.5). At depths of 2–4 km, Tmax values (435–450 °C) from organic-rich layers of the Sargelu, Garau and Kazhdumi source rocks in the Kuh-e-Asmari anticline indicate mid to late mature stages of hydrocarbon generation. One dimensional thermal models allowed us to define the onset of oil generation for the Middle Jurassic to Eocene source rocks and pointed out that sedimentary burial is the main factor responsible for measured levels of thermal maturity. Specifically, the Sargelu and Garau Formations entered the oil window prior to Zagros folding in Late Cretaceous times, the Kazhdumi Formation during middle Miocene (syn-folding stage), and the Pabdeh Formation in the Late Miocene–Pliocene after the Zagros folding. In the end, the present-day distribution of oil fields in the Dezful Embayment and gas fields in the Fars region is primarily controlled by lithofacies changes and organic matter preservation at the time of source rock sedimentation. Burial conditions during Zagros folding had minor to negligible influence.

The present work provides a combined structural and paleothermal (fluid inclusions, illite content in mixed layers illite–smectite, Kubler index and vitrinite reflectance) investigation of the Alpine cleavage domain affecting the western South Pyrenean Zone (Central Pyrenees). Integration of structural and paleothermal data allows us (i) to determine the position of the cleavage front in the sedimentary sequence and (ii) to define mechanisms and temperature conditions for cleavage development. Cleavage in the eastern part of the study area is approximately limited to the forelimb of the Gavarnie hanging wall anticline, but to the West it extends progressively southwards, affecting younger turbiditic units. At regional scale, the cleavage front is oblique to the strike of bedding and the overall trend of macrostructures. Pressure-solution is the main mechanism for cleavage development, and a strong thermal control on the position of the cleavage front is inferred. The transition between sedimentary and tectonic, compressional fabric is marked by vitrinite reflectance values of 1.12–1.14%, Kubler index values between 0.71 and 0.74°Δ2θ and the transition between R1 and R3 mixed layers illite–smectite. A lower thermal boundary of 140–160 °C is suggested for incipient cleavage development in the shaly beds of the turbiditic sequence, as well as an upper boundary constrained by a maximum measured value of about 215 °C.

[1] Obtaining constraints on maximum earthquake energy from fossil geological evidence has a primary importance for complementing historical information toward the proper mitigation of seismic hazard in a region. In this paper, we describe a newly discovered extensional fault zone in the western L'Aquila basin (Italy), associated with large paleofluidization structures. Paleofluidization-bearing Calabrian sediments provide evidence for very shallow burial from mineralogical, organic matter thermal maturity, and flat dilatometer test data, whereas density of organic matter shows anomalously high values. We propose that all these pieces of information can be reconciled into a paleoseismological scenario where sediment liquefaction and fluidization in early middle Pleistocene times, as well as dewatering and overconsolidation, were coseismically triggered by strong earthquakes with magnitude approaching or slightly exceeding 7.0.

Poland is considered the most prospective country for shale gas production in Europe. Hydrocarbon generation/expulsion scenarios, drawn in the latest intensive exploration phases, tend to overestimate maturation levels when compared with brand new data acquired after recent drillings. We tested an integrated workflow to correlate published and original thermal maturity datasets for the Paleozoic to Jurassic successions cropping out in the Holy Cross Mountains. These successions, when preserved in subsurface, host the major source rocks in the area. The application of the workflow allowed us to highlight the burial and thermal evolutionary scenarios of the two tectono-stratigraphic blocks of the Holy Cross Mountains (Łysogory and Kielce blocks) and to propose this approach as a tool for reducing levels of uncertainty in thermal maturity assessment of Paleozoic successions worldwide. In particular, published datasets including colour alteration indexes of Paleozoic microfossils (conodont, acritarchs) and vitrinite and graptolite reflectance data, show differences in levels of thermal maturity for the Łysogory (mid mature to overmature) and Kielce (immature to late mature) blocks. Original data, derived from optical analysis, pyrolysis, and Raman spectroscopy on kerogen, and X-Ray diffraction on fine-grained sediments, mostly confirm and integrate published data distribution. 1D thermal models, constrained by these data, show burial and exhumation events of different magnitude, during the Late Cretaceous, for the Łysogory (maximum burial depths of 9 km) and Kielce (burial depths of 6 km) blocks that have been related to the Holy Cross Fault polyphase activity. In the end, Palynomorph Darkness Index and Raman spectroscopy on kerogen, for Llandoverian and Cambrian rocks, turned out to be promising tools for assessing thermal maturity of Paleozoic organic facies devoid of vitrinite macerals.

Cap rock characterization of geothermal systems is often neglected despite fracturing may reduce its efficiency and favours fluid migration. We investigated the siliciclastic cap rock of Rosario de La Frontera geothermal system (NW Argentina) in order to assess its quality as a function of fracture patterns and related thermal alteration. Paleothermal investigations (XRD on fine-grained fraction of sediments, organic matter optical analysis and fluid inclusions on veins) and 1D thermal modelling allowed us to distinguish the thermal fingerprint associated to sedimentary burial from that related to fluid migration. The geothermal system is hosted in a Neogene N-S anticline dissected by high angle NNW- and ENE-striking faults. Its cap rock can be grouped into two quality categories: • rocks acting as good insulators, deformed by NNW–SSE and E–W shear fractures, NNE-SSW gypsum- and N-S-striking calcite-filled veins that developed during the initial stage of anticline growth. Maximum paleo-temperatures (< 60 °C) were experienced during deposition to folding phases.• rocks acting as bad insulators, deformed by NNW-SSE fault planes and NNW- and WNW-striking sets of fractures associated to late transpressive kinematics. Maximum paleo-temperatures higher than about 115 °C are linked to fluid migration from the reservoir to surface (with a reservoir top at maximum depths of 2.5 km) along fault damage zones.This multi-method approach turned out to be particularly useful to trace the main pathways of hot fluids and can be applied in blind geothermal systems where either subsurface data are scarce or surface thermal anomalies are lacking. Fil: Maffucci, R.. Universita Degli Studi Della Tuscia; Italia. Universita Degli Studi Roma Tre; Italia Fil: Corrado, Sveva. Universita Degli Studi Roma Tre; Italia Fil: Aldega, L.. Instituto de Investigaciones Universitarias Roma la Sapienza; Italia Fil: Bigi, S.. Instituto de Investigaciones Universitarias Roma la Sapienza; Italia Fil: Chiodi, Agostina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentina Fil: Di Paolo, L.. Eni E&P Division; Italia Fil: Giordano, G.. Universita Degli Studi Roma Tre; Italia Fil: Invernizzi, C.. Universita Degli Di Camerino; Italia

Vitrinite reflectance has been always considered the most reliable thermal maturity indicator in sedimentary basins. Nevertheless the reliability of vitrinite reflectance measurements can be affected by many external factors that change from basin to basin (e.g. organic facies, temperature and pressure conditions) leading to wide uncertainties in thermal modelling calibration and thus in the evaluation of timing and amount of hydrocarbons generation. We demonstrate that in case of vitrinite suppression and/or retardation in siliciclastic successions, the classical Sweeney and Burnham kinetics do not match the actual thermal evolution of the basin. In these cases, thermal evolution can be successfully modelled using a complementary approach based on smectite illitization kinetics or more appropriate kinetics (e.g., PresRo TM and T-P-Ro) to evaluate the effect of pressure on organic matter maturation where pressure data are available. This approach was applied in the Lower Congo Basin where 32 cuttings from a 5 km-deep well drilled in the Upper Oligocene-Miocene Malembo formation have been analysed to derive organic and inorganic constraints to model the basin thermal evolution. Vitrinite and bitumen reflectance measurements show values between 0.3 and 1.0% along the well, whilst the illite content of mixed layer I-S ranges between 35 and 88%, passing from R0 to R1 to R3 stacking order with increasing depth. Present-day temperature distribution through the well indicates a geothermal gradient of about 40 °C/km and measured pressures show an overpressured interval between 3 and 4 km depth. Retardation and suppression phenomena affected vitrinite reflectance in this interval but did not influence smectite illitization. The comparison between thermal maturity scenarios constrained by organic and inorganic thermal indicators shows differences in the calculation of the depth of the onset of hydrocarbon generation that is overestimated of about 500 m in the Lower Miocene interval when only suppressed/retarded vitrinite reflectance values are used to calibrate models.

Coeval extensional and contractional tectonics are a common feature in orogenic belts, especially in post-collisional phases. The attempt to constrain their relative timing and the responsible mechanisms led to several models taking into account different geodynamic contexts of various mountain chains. In peri-Mediterranean collisional orogens, extension and compression are commonly associated and coeval to the emplacement of far-travelled/allochthonous units. Therefore their internal deformation acquired during the translation across collisional belts is likely imprinted by the extensional and contractional tectonics affecting the orogen.In the western portion of the Northern Apennines of Italy, one of the northernmost peri-Mediterranean Tertiary orogens, the far-travelled/allochthonous units, i.e., the Ligurian and Subligurian units, are widely exposed. The present study integrates published and newly acquired surface geological data (geological maps, cross-sections), subsurface boreholes data, and paleothermal (vitrinite reflectance, mixed layer illite-smectite and Kübler index) and thermochronological data (apatite fission-tracks) in order to investigate the deformation history and, consequently, the record of the extension-compression relationships within these far-travelled/allochthonous units.The study of modes and timing of reshaping of the far-travelled/allochthonous units allowed us to strengthen the hypothesis that extensional and contractional tectonics were coeval in the Northern Apennines and tightly connected by a cause/effect relationship. In particular, the late orogenic low- and high-angle extensional tectonics represent the response to an overall contractional regime which induced episodes of gravitational instability in the orogenic wedge. © 2013 Elsevier B.V.

Combined structural and geophysical investigations were carried out in the Matese Massif at the boundary between the Central and the Southern Apennines. The aim of this research was to define the structural geometry and the kinematics of Neogene deformation in order to validate the applicability of either thin-skinned or thick-skinned compressive styles in the Apennines of Italy. On the basis of two surface N–S cross-sections, integrated with recently acquired magnetotelluric data, the Matese structure appears as a single thrust sheet limited at the bottom by a low-angle thrust fault with sense-of-displacement towards the North. The structure was later deformed by footwall thrusts carrying Molise–Sannio Pelagic Basin Units and Apulian Carbonate Platform Units. The structure of the Matese Massif is composed mainly of Mesozoic carbonates of inner platform to by-pass and slope facies, separated within the thrust sheet by high-angle faults with low reverse horizontal displacement. These faults acted as normal faults in the Mesozoic and Cenozoic and controlled the carbonate facies distribution. During Neogene compression, these structures were tilted and then truncated by the basal short-cut thrust fault that cut from pre-Triassic units to Jurassic dolostone towards the foreland. Finally, Quaternary extensional tectonics dissected the whole structure with fault-related displacement values of up to 1000 m. This resulted in the present-day structural setting of the Matese Massif as a horst bounded to the SW and NE by fault-controlled basins, filled with continental deposits. This revised structural scenario is discussed within the framework of the structural style of external zones of the Apennines.

This paper focuses on the boundary area between the Central and Southern Apennines thrust belt of the Italian peninsula, which separates two different patterns of distribution of active faults and strong earthquakes along the Apennines chain. In order to reduce the remarkable lack of data on this area, part of this boundary has been investigated. The study area corresponds to the surroundings of the town of Isernia, an important centre of the Molise region, and contains the Carpino and Le Piane (CLP) intermountain Basins of Quaternary age. The research was based on unpublished data, consisting of 65 well logs drilled in the CLP Basins, integrated with detailed field surveys (scale 1:10,000), mesoscale structural analysis and aerial photograph interpretation. This study allowed to define the geometry and kinematics of the CLP Basins. They result to be asymmetric halfgrabens partially filled with fluvio-lacustrine deposits, where the sedimentation is controlled by the activity of a set of normal faults striking N30jW and NE dipping. This set of faults, which developed mainly during the Late Pleistocene–Holocene, is about 10 km long and is located close to the northwestern end of the Boiano Basin extensional Fault System. The average slip rate calculated for part of the Holocene for one of the recognised faults ranges from 0.75 to 1.00 mm/year. The identification of the active CLP Basins Fault System partially fills the gap of data at the boundary between the Central and Southern Apennines. From a more general point of view, we hypothesise that this boundary might be regarded as a ‘‘persistent segment boundary’’, forming a long-term barrier to the propagation of rupture of active fault systems. Under this perspective, a redefinition of the seismic zonation of Italy for the study area is suggested. D 2002 Elsevier Science B.V. All rights reserved.

The Monte Alpi area of the Southern Apennines represents the only sector of the thrust belt where the reservoir rocks (i.e. Apulian Platform carbonates) for major hydrocarbon accumulations in southern Italy are interpreted to crop out. Tectonic evolution and exhumation of this area were analysed by integrating stratigraphic and structural data with different organic and inorganic parameters which record the burial and thermal evolution of the sediments (vitrinite reflectance, fluid inclusions, and I/S mixed layers in clayey sediments). Our analyses suggest that the presently exposed Monte Alpi structure suffered a loading of ca. 4000 m, owing to the emplacement of allochthonous units in Early Pliocene times. Available geological data indicate that erosion of the tectonic load occurred since the Late Pliocene, when the area first emerged. This implies an average exhumation rate in excess of 1 mm/year. A model can be constructed which matches the maturity indices and also takes into account intermediate stages of the evolution, resulting from combined structural and fluid inclusion data. By this model, a first stage of exhumation would have taken place at an average rate of about 0.36 mm/year. This was controlled by uplift and erosion associated with both: (i) thrusting at depth within the Apulian carbonates (Late Pliocene), and (ii) strike-slip faulting (Early Pleistocene). A second exhumation stage would have occurred in the last 700 ky at a much faster rate (ca. 4 mm/year) as a result of extensional tectonics. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.

The Abruzzi–Molise sector in the Central Apennines is a part of a fold and thrust belt that has been deforming since the Late Cretaceous as a result of collision tectonics between the European and Adriatic plates. The superposition of different deformational styles highly reworked the originally complex palaeogeography of this portion of the southern Tethyan margin. Analogue modelling has been performed on thrusting mechanisms in the Abruzzi–Molise area in order to (1) reduce the number of admissible hypotheses regarding palaeogeographic setting, and (2) define thrusting mechanics. Both of these goals are crucial for hydrocarbon exploration purposes. The sandbox apparatus used to simulate the undeformed passive margin consisted of a thin compartment juxtaposed against a thick one along a linear boundary having variable geometries and mechanical stratigraphy; a rigid but mobile backstop was used to deform the stratigraphy in a Coulomb thrust wedge. Results from six experiments show that the geometric relationships between different structural units depend on the distribution of palaeogeographic domains. These domains are defined by mechanical and/or geometrical parameters, such as the orientation between the maximum compression direction and the palaeogeographic boundary, the mechanical stratigraphy and the thickness of the successions reproduced in the models. The present-day tectonic styles and Meso–Cenozoic palaeogeography of the Abruzzi–Molise area are discussed in terms of the mechanisms and structures analysed through the models.

The Abruzzo-Molise-Sannio region is part of the Central Apennines foreland fold and thrust belt, a structure that formed during the Neogene as a result of the continental collision between the European and Adria plates. Certain areas of this crust experienced anomalously high temperatures due to deep burial, while others did not. This burial has been investigated using optical indicators of organic matter (OM) maturity and clay mineralogy. The maximum depths of burial of Tertiary surface sequences have been established based on the vitrinite reflectance (Ro) and thermal alteration index (TAI) of OM dispersed in synorogenic sediments and from clay mineralogy of pre-thrusting clayey deposits. The synorogenic deposits show low levels of organic maturity having Ro values less than 0.6% indicating early mature to mid-mature hydrocarbon generation. The pre-thrusting deposits are shales characterised by a very high percentage of clay minerals with lesser amounts of quartz, K-feldspar, plagioclase and calcite. The dominant minerals are highly smectitic interstratified illite/smectite (RIS). Both Ro and I/S ratios were used to calibrate burial and thermal evolution of this chain sector by numerical modelling. The results indicate that the structural units which outcrop in the study area (particularly the Molise Unit) were never overthrust by significant thicknesses of rocks during mountain building, at least before Pliocene times; the hypothesis that more internal units overthrust the presently exposed units also seems to be unlikely.

Determining the deposit temperature of pyroclastic density currents (PDCs) is a first order priority in the assessment of volcanic hazard. For past eruptions, in which no direct measurements are possible, PDC deposit temperatures have been calculated mainly using magnetic proxies. A more recent and innovative approach consists of the determination of the degree of charring of preserved wood fragments by optical analysis. In this study, we perform optical analyses on wooden beams belonging to the Villa dei Papiri at the archeological site of Herculaneum, which was destroyed by PDCs during the 79 AD eruption of Vesuvius. The new temperature data from this study range between 240 °C and 370 °C, and are in good agreement with literature data for this eruption. The large T variation measured can be interpreted as due to the interaction of the PDCs with the local environment, i.e. the impacted buildings of the villa and the sea shoreline. The study of in situ charred wood allows to constrain the charring kinetics and to evaluate the sensitivity of the reflectance proxy in recording PDC depositional features. We demonstrate that the charcoal reflectance is an excellent proxy for the determination of the PDC deposit temperatures even at a local scale, and it can be used in conjunction with, or in alternative to other more traditional methodologies, especially in case of pre-heating effects which may alter the T determinations by thermoremanent magnetization.

We integrated X-ray diffraction (XRD) data concerning the illite content in mixed-layer illite–smectite with data derived from Fourier Transform Infrared spectroscopy (FTIR) on H-rich organic matter to constrain the burial-exhumation path of the Mt. Judica sedimentary succession cropping out in tectonic window in Eastern Sicily. Thermal structural model constrained by organic and inorganic thermal parameters showed that the Mt. Judica succession experienced paleo-temperatures in the range of 100–130 °C in deep diagenetic conditions and early mature stage of hydrocarbon generation. Specifically, the illite content in mixed-layer I–S ranges from 50 to 76% and FTIR-derived indexes suggest a thermal maturity equivalent to VRo values of at least 0.5–0.7%. As a whole, the Mt. Judica succession experienced maximum tectonic burial (ranging between 2.4 and 3.2 km) during the Middle Miocene as a result of the emplacement of the allochthonous units atop it. The subsequent breaching phase characterized by up-thrust geometries, and erosion during Pliocene times ruled out the Mt. Judica exhumation. This last tectonic phase did not overprint thermal maturity because the extent of overthrusting was negligible when compared with the magnitude of vertical movements. Restoration of balanced cross sections revealed an increase of shortening from the salient to the Mt. Judica recess with values from 12.3 to 23.9 km, consistent with the increase of tectonic thickening of the fold-and-thrust belt. Integration of maximum burial and shortening values along the curvature of the Sicilian fold-and-thrust belt allowed us to reconstruct the wedge paleo-geometry in the Mt. Judica recess area, to investigate the along-strike variations of the tectonic overburden, and to discuss the geodynamic causes of these changes. These results were compared with theoretical models of wedge dynamics.

Vitrinite reflectance and mineralogical data from 55 samples collected from the Mt. Cervarola Sandstones and the Granaglione Sandstones (thrust-top basin Cervarola Successions) testify the severe thermal maturity of the present-day outcropping successions. This is due to the deep tectonic burial the successions underwent during Miocene chain building. Lower levels of thermal maturity are recorded in the Mt. Cervarola Sandstones. They form a thick upper thrust sheet (Ro% ranging between 1.0 and 1.2%; I% in I/S mixed layers ranging between 80 and 85%). Higher levels of thermal maturity characterise the structurally lower thrust sheets, made up mainly of Granaglione Sandstones (Ro% ranging between 1.2 and 1.5%; and I% in I/S mixed layers between 85 and 90%). Maturity generally decreases from hinterland to foreland. Integration of Ro% and I% in I/S data with published low-temperature indicators allowed to reconstruct a maximum tectonic burial ranging between ∼3.5 on the upper thrust sheet and ∼5 km on the lower ones. Burial was mainly due to the early emplacement of the Ligurian Unit and the Modino Unit on top of the studied units and to later piggy-back thrusting of the Mt. Cervarola Sandstones onto the Granaglione Sandstones. © 2004 Lavoisier SAS. All rights reserved.