The Permian deposits of Hydra Island (Greece), micropaleontology, sedimentology and paleoenvironments,Le Permien de l'île d'Hydra (Grèce), micropalé ontologie, sédimentologie et paléoenvironnements

This study presents severa! analyses in micropaleontology and scdimentology of four sections of permian deposits in the Hydra Island (Grecce). The micropaleontological study is an inventory of foraminifers and aigne, which allow securnte datations to precise age assigncmcnts. Rcprcscntaûvc facies have bccn dcfined for the Permian deposits. Summary of these data pcrmitted to eharacterize successive paleocnvironments and to propose a reconstruction of Permian sequences in this arc

Contrasting reef patterns during the evolution of the carboniferous azrou-khenifra basin (Moroccan Meseta)

Five types of reefs are described from the northern and southern parts of the Azrou-Khenifra Basin generated by the interactions of microbes and coral communities. The type 1 microbial reefs grew in both shallow- and deep-water settings, with a strong control by glacioeustasy. Type 2 microbial reefs developed in more tranquil periods, associated with common intermounds, and where only a single major regressive-transgressive sequence is recognised. Type 3 microbial reefs developed in constant deeper water conditions, generated by higher rates of subsidence in the basin, and creating an overall deepening-upward sequence. Type 4 microbial reefs recognised in the northern part of the basin have no clear counterparts in southern outcrops, but they are likely the capping strata observed in the latter area. Rugose corals allow to define a Type 5 reef, unrelated to microbial facies, and are recorded in oolitic-bioclastic backshoals or quiet inner platform settings. The presence of similar reefs in both the northern and southern parts of the basin demonstrates that conditions were not as different as previously proposed, and a lithostratigraphical, environmental uniformity occurs, which permits the analysis of different subsidence rates and glacioeustastic influence. In the Azrou-Khenifra Basin, the reefs, as well as other regional features, suggest that the basin, overall, evolved from an extensional tectonic regime during the early Brigantian into a complex extensional or compressional regime during the early Serpukhovian, passing into a predominantly compressional phase during the late Serpukhovian in a polyphase tectonic inversion during the onset of the Variscan Orogeny in the region

Les bassins carbonifères de la Méséta marocaine, étude sédimentologique et approche du contexte structural. Part de la tectonique et de l'eustatisme

The carboniferous basins of the moroccan Meseta, the sedimentary proofs and the approach of the tectonic setting. Tectonics versus eustacy. The distribution of the carboniferous sedimentary basins, the nature of their filling, the curves of the cumulative thickness of the sediments in relation to the time and the curves of the tectonic and thermal subsidence allow to test the geotectonic models propounded for the moroccan Meseta and to compare the Morocco with the Europe. The curves of the tectonic and thermal subsidence are polyphase with a sharp slope with or without a decreasing of the subvidence. They are inside the domain of the strike slip basins (Mc CABE, 1991) with or without a thermal relaxation. At the N and S of the eastern Meseta, during the collision, these basins become foreland basins with gliding nappes, consequently they are composite basins. These basins are filled by continental or marine deposits that depend on the tectonics and the eustacy. The upper Visean is a period of the maximum transgression on the Meseta. During the Namurian and the Westphalian, the sea recedes to the East near the Mesogée. We watch the global eustatic events in the moroccan Meseta during the Carboniferous.La répartition des bassins sédimentaires, la nature de leur remplissage, les courbes de l'épaisseur cumulée des sédiments et les courbes de subsidence tectonique et thermique permettent de tester les modèles géotectoniques proposés pour le Carbonifère du Maroc et de comparer le Maroc avec l'Europe. Les courbes de subsidence tectonique et thermique sont polyphasées du type forte pente avec ou sans diminution de la subsidence. On peut les rattacher au type bassin sur décrochement (Me CABE, 1991) avec ou sans relaxation thermique. Au N et au S de la Meseta orientale, lors de la collision, ces bassins se transforment à la fin du Viséen supérieur en bassin d'avant-pays avec mise en place de nappes de glissement, d'où un caractère mixte. Le remplissage des bassins par des faciès continentaux ou marins est fonction de la tectonique et de l'eustatisme. Le Viséen supérieur est la période de transgression maximale sur l'ensemble de la Meseta. Au Namurien et Westphalien, l'influence marine ne reste importante qu'à proximité de la Mésogée à I'E. Les variations eustatiques globales s'observent en Meseta marocaine au Carbonifère.Izart Alain. Les bassins carbonifères de la Méséta marocaine, étude sédimentologique et approche du contexte structural. Part de la tectonique et de l'eustatisme. In: Géologie Méditerranéenne. Tome 18, numéro 1-2, 1991. Le paleozoïque du Maroc. II – Carbonifère – Permien (Paléontologie – Biostratigraphie – Aspects structuraux) pp. 61-72

The Sarro-Lorraine Basin (SLB) in the frame of the Variscan orogeny: structure and tecto-sedimentary schedule

International audienceThe Sarro-Lorraine Basin (SLB) is only known in subsurface in the eastern part of the Paris Basin beneath the Mesozoic sedimentary cover. It is the western extension of the Saar-Nahe basin outcropping in Germany. The nature of its sedimentary filling, of Pennsylvanian (Westphalian-Stephanian) to Permian age, is known through numerous coal and oil exploration wells, most of which drilled before the 1990s. The sedimentary deposits consist of clayey to conglomerate silicoclastic sediments rich in coal (mainly Westphalian), typical of fluviolacustrine environments. Significant uncertainties remain regarding the structure of the SLB, mainly due to the limited number of seismic profiles available to the scientific community. The commonly accepted hypothesis (based among other things on rare seismic profiles dating from the 1960s) proposes that the subsidence initiated in the Namuro-Westphalian and continued at least until the beginning of Permian times. The sedimentation would have been controlled by a network of normal faults (e. g. the Metz fault) located in the north of the future basin, potentially with a strike-slip component. In order to remove the uncertainties mentioned above and to question the established interpretation, the BRGM (French Geological Survey) and the University of Lille (France), in addition to 175 km reprocessed by BRGM, have recently reprocessed more than 180 km of industrial seismic lines acquired in the 1980s. The interpretation of these seismic profiles reprocessed with modern methods gives a new image of the geometry and cartographic extension of the SLB (e.g. the clear unconformity between the Westphalian and Stephano-Permian sedimentary series, Permian post-rift deposits, possible extension of the SLB to the north beyond the Metz fault). We interpret the observed sedimentary and structural geometries in terms of negative tectonic inversion at the end of the Variscan orogenic process: the normal faults controlling the stephano-permian sedimentation ("rifting") are thus rooted in the thrusts coeval with the Westphalian molasse-like sedimentation. In order to place the SLB in the Variscan geodynamic context, these new observations are confronted with Variscan deformations known further east in Germany, where they are described in details; the SLB would then record the syn-to post-orogenic evolution (according to the tectonic inversion process) of a segment of the Saxo-Thuringian zone directly south of the Rheno-Hercynian suture

The Sarro-Lorraine Basin (SLB) in the frame of the Variscan orogeny: structure and tecto-sedimentary schedule

International audienceThe Sarro-Lorraine Basin (SLB) is only known in subsurface in the eastern part of the Paris Basin beneath the Mesozoic sedimentary cover. It is the western extension of the Saar-Nahe basin outcropping in Germany. The nature of its sedimentary filling, of Pennsylvanian (Westphalian-Stephanian) to Permian age, is known through numerous coal and oil exploration wells, most of which drilled before the 1990s. The sedimentary deposits consist of clayey to conglomerate silicoclastic sediments rich in coal (mainly Westphalian), typical of fluviolacustrine environments. Significant uncertainties remain regarding the structure of the SLB, mainly due to the limited number of seismic profiles available to the scientific community. The commonly accepted hypothesis (based among other things on rare seismic profiles dating from the 1960s) proposes that the subsidence initiated in the Namuro-Westphalian and continued at least until the beginning of Permian times. The sedimentation would have been controlled by a network of normal faults (e. g. the Metz fault) located in the north of the future basin, potentially with a strike-slip component. In order to remove the uncertainties mentioned above and to question the established interpretation, the BRGM (French Geological Survey) and the University of Lille (France), in addition to 175 km reprocessed by BRGM, have recently reprocessed more than 180 km of industrial seismic lines acquired in the 1980s. The interpretation of these seismic profiles reprocessed with modern methods gives a new image of the geometry and cartographic extension of the SLB (e.g. the clear unconformity between the Westphalian and Stephano-Permian sedimentary series, Permian post-rift deposits, possible extension of the SLB to the north beyond the Metz fault). We interpret the observed sedimentary and structural geometries in terms of negative tectonic inversion at the end of the Variscan orogenic process: the normal faults controlling the stephano-permian sedimentation ("rifting") are thus rooted in the thrusts coeval with the Westphalian molasse-like sedimentation. In order to place the SLB in the Variscan geodynamic context, these new observations are confronted with Variscan deformations known further east in Germany, where they are described in details; the SLB would then record the syn-to post-orogenic evolution (according to the tectonic inversion process) of a segment of the Saxo-Thuringian zone directly south of the Rheno-Hercynian suture

Mississippian (middle Tournaisian-late Serpukhovian) lithostratigraphic and tectonosedimentary units of the southeastern Montagne Noire (Hérault, France)

The tectonosedimentary and lithostratigraphic units of the Mont Peyroux nappe and Cabrières klippes, in the southeastern Montagne Noire, are revised. The Mont Peyroux nappe displays two Mississippian groups: SaintNazaire-de-Ladarez and Barrac. The Saint-Nazaire-deLadarez Group includes the traditional formations of Lydiennes, Faugères and Colonnes. The Barrac Group (new group) encompasses the Puech Capel Fm (with two new members: Puech Capel Mb and Landeyran Barn Mb), and the new Barrac and Fabrègues formations. The Puech Capel Mb corresponds to a period of erosion, reworking, and debris flow deposition in the basin, linked to a major tectonic event; hence, the distinction between two groups is made here. The Barrac Fm, overturned and normal, with classical Bouma turbidites, and without carbonate olistoliths, ends west of the Fabrègues Formation, bearing a few latest Viséan to Serpukhovian olistoliths. The Cabrières klippes contain numerous Ordovician, Silurian, Devonian and Mississippian klippes and olistoliths included in a detrital unit (formerly Flysch-units III-IV or Laurens Flysch Group); they are re-named here as the Laurens-Cabrières Group, and subdivided into three new complexes: the Laurens Complex, Roquessels Complex and Vailhan-Cabrières Complex. The Laurens Complex is not yet subdivided into formations. The Roquessels Complex shows characteristically the new Coteau de Bergue Fm and the Lentilles de la route D13 informal unit (including the former grauwacke de Roquessels). The Vailhan-Cabrières Complex is composed of three klippes: Vissou, La Serre and Tourière-Escandolgue -Mougno (TEM), and various disseminated smaller olistoliths, which are Early Ordovician to late Serpukhovian (Protvian) in age. The Vissou klippe probably corresponds to a fragment of the overturned limb of the Mont Peyroux nappe, because it exposes the traditional inverse succession of the Saint-Nazaire-de-Ladarez Group, followed by the equivalent of the Puech Capel Mb, with carbonate slumps and sandy turbidites. In the La Serre klippe, a new La Serre East Fm is described as the unique formation of Montagne Noire with late Tournaisian-early Viséan shallow carbonates. In the Vailhan-Cabrières Complex, several formations are defined or redefined in the Mississippian klippes and olistoliths: Tourière Fm (former secondes griottes), Combe Rolland Fm (former bancs de dessus), Valuzières Fm (former calcaires du sommet 224- Valuzières), Oolites of Roc de Murviel Fm, Roque Redonde Fm, Roc de Murviel Fm, and La Serre de Péret Fm. The four latter formations correspond to the former Calcaires à Productus. The Laurens-Cabrières Group in Cabrières is relatively distinct, and exhibits possible prodeltaic units within the poudingue à dragées (candy conglomerates), sandstone with “Namurian A” terrestrial plants fragments, and Phillipsia sandstones, designated here as the MougnoLes Batailles informal unit. Some carbonate units associated with these prodeltaic deposits, such as the Spanish Scarf and other “bioherms of Cabrières”, seem to be affected by small displacements (Escandolgue, Japhet). Palaeogeographic and tectonic implications lead to the structural hypothesis of a Mont Peyroux-Cabrières unit, including together the Mont Peyroux nappe and the Cabrières klippes, which initially was thrust and deposited in the Axial Zone, and then glided southward to its current location.P. Cózar benefitted from a financial support of the Spanish Ministerio de Economía y Competitividad (research project CGL2016-78738).Peer reviewe

Histoire thermique et interactions fluides-roches dans l'Est du Bassin de Paris

A l'Est du Bassin de Paris, la superposition de roches sédimentaires aux propriétés hydrauliques, thermiques et mécaniques contrastées forme un système géologique compartimenté. Les séries aquifères du Jurassique moyen et supérieur et du Trias (faciès Buntsandstein) sont séparées par des niveaux aquitards constitués d'évaporites et d'argiles, parmi lesquelles la succession callovo-oxfordienne épaisse de 150 m, sélectionnée par l'agence nationale pour la gestion des déchets radioactifs (Andra). Retracer l'histoire thermique des séries sédimentaires mésozoïques et lier cette histoire aux processus d'interactions fluides-roches ayant modifié les propriétés pétrophysiques des formations perméables constitue la problématique centrale de ce travail de thèse. Ce mémoire présente, dans une première partie, une synthèse de l'évolution thermique des séries mésozoïques, s'appuyant sur des données géothermométriques (réflectance de la vitrinite, isomérisation des biomarqueurs moléculaires, inclusions fluides) et sur la modélisation numérique du bassin. Dans une seconde partie, les propriétés physico-chimiques des paléo-fluides ayant percolé dans les aquifères carbonatés du Jurassique moyen et supérieur sont recherchées à l'aide des teneurs en éléments traces et de la composition isotopique (d18O, d13C, 87Sr/86Sr) des phases minérales authigènes, couplée aux mesures de chlorinité et des rapports D/H des eaux piégées en inclusions fluides. Dans les grès du Trias, les datations K-Ar de fractions granulométriques riches en illite documentent deux périodes de cristallisation à 179.4 +- 0.8 Ma et 149.4 +- 0.3 Ma, respectivement durant le Lias et à la période fini-Jurassique / début CrétacéIn the eastern Paris Basin, the succession of sedimentary rocks with variable hydro-thermo-mechanical properties leads to a compartmentalization of the system. Three aquifer units - the Middle and Upper Jurassic limestones and the Lower Triassic sandstones - are apart from each other by very low-permeable evaporites and clay-rich successions, among which the Callovian-Oxfordian claystones currently investigated by the French national radioactive waste management agency (Andra). This PhD thesis deals with the thermal history reconstruction and the fluid-rock interactions in the Mesozoic series through a multidisciplinary approach. In the first part of the manuscript, the P-T evolution of the Mesozoic series is documented based on thermal indicators (vitrinite reflectance, biomarker isomerization, fluid inclusions) and numerical modeling. In the second part, major and trace element concentrations (including REE) and isotopic compositions (d18O, d13C and 87Sr/86Sr) of authigenic minerals and fluid inclusions were used to estimate the origin of paleo-fluids and their evolution through water-rock interactions. In the Lower Triassic sandstones, K-Ar dating of authigenic illite documents two periods of crystallization at 179.4 +- 0.8 Ma and 149.4 +- 0.3 MaMETZ-SCD (574632105) / SudocNANCY1-Bib. numérique (543959902) / SudocNANCY2-Bibliotheque electronique (543959901) / SudocNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Genèse des hydrocarbures des séries infrasalifères de la partie Est du bassin Précaspien (Kazakhstan)

Objectifs de la thèse sont la caractérisation des roches mères, du degré du maturation de la matière organique, la reconstruction de la génération des hydrocarbures dans les formations antesalifères (Devonien, Carbonifère et Permien) de la partie Est du bassin Précaspien. Cette étude a permis de déterminer les faciès de pente au Carbonifère et leur progradation sur la plate-forme carbonatée d'âge Carbonifère pendant le Permien inférieur. Trois séries ont été identifiées comme roches mères : les calciturbidites du Serpukhovien-Moscovien à matière organique (MO) de type II marin (1) ; les turbidites du Viséen inférieur-moyen (2) et du Permien inférieur (3) à MO de type III continental et d origine mixte - II/III. Les roches mères du Viséen et du Permien inférieur sont les sources les plus importantes d hydrocarbures. Les roches mères ont été corrélées avec les huiles des réservoirs de même âge. Les échantillons étudiés ont généralement une faible maturité avec des PRV < 0,75 et des Tmax < 440C. Le bassin Précaspien semble assez froid, le bassin Préouralien est plus chaud sous le chevauchement où les roches mères étudié ont atteint les conditions de la fenêtre à gaz. Ceci est confirmé par la modélisation Petromod 1D. Quatre zones dans lesquelles les profondeurs du début et de fin de la fenêtre à huile sont différentes ont été distinguées : la zone Ouest (bassin) : de 4 - 9 km ; la zone de pente et de Bordure : de 3 - 6 km ; le bassin Préouralien : de 2,8 - 5 km; la zone Nappe (Izembet) : de 2 - 4 km. Les âges éventuels de piégeage d inclusions aqueuses et hydrocarbonées correspondent au Permien, ce qui permet d estimer la période de migration du pétrole.Aims of the thesis are the characterization of source rocks, of degree of maturity of the organic matter, the building of the genesis of hydrocarbons in the subsalt formations (Devonian, Carboniferous, Permien) of eastern part of the Precaspian Basin. This study allowed to determinate two facies of slope, the first (calciturbidites and breccia) during the Carboniferous and the second (turbidites) with downlap on the Carboniferous carbonated platform during the early Permian. The following formations were classed as source rocks : the calciturbidites of Serpukhovian, Bashkirian and Moscovian with organic matter (OM) of type II (marine); the turbidites of early and mid-Visean, and early Permian with OM of type III (continental) and mixture of type II and III. The turbiditic source rocks from Visean and early Permian are the most significant source of hydrocarbons. The source rocks correlate with the oil of the same age of reservoirs. The studied samples own generally a low maturity with Vitrinite reflectance lower than 0.75, Tmax lower than 435C. The Precaspian basin seems the coldest, the Preuralian basin is the hottest under the thrust of Ural where these rocks are inside the gas window. This fact is confirmed by the Petromod modelling. After all these data, we can distinguish four zones in which the depths of the beginning and end of the oil window are different: the western zone (basin) from 4 - 9 km, the zone of slope and border from 3 - 5 km, Preuralian basin from 2,8 - 5 km, and the eastern zone under the thrust of Ural (Izembet) from 2 - 4 km. The ages of trapping of fluid inclusions correspond to Permien, which allow to estimate the periode of oil migration.NANCY1-SCD Sciences & Techniques (545782101) / SudocSudocFranceF

Late Viséan–Serpukhovian foraminifers in the Montagne Noire (France): Biostratigraphic revision and correlation with the Russian substages

The “calcaires à Productus” of the Montagne Noire (Aude-Hérault, southern France) are carbonate lenses embedded within a thick Carboniferous siliciclastic complex. Foraminiferal assemblages in some of the larger carbonate lenses are typically representative of the late Viséan and Serpukhovian. Eleven new species of foraminifers are described: Hemidiscopsis variabilis, H. pilleae, Planohowchinia rara, P. redondensis, Spireitlina minima, Rectoendothyra japhetensis, Mikhailovella enormis, Cribrospira? perretae, Pojarkovella occidentalis, Parabiseriella vailhanensis, and Biseriella delicata. Eight foraminiferal biozones are defined; they are based on the first occurrence of some taxa, and could be used for other regions of southern France (e.g., Mouthoumet and the Pyrenees). These biozones are informally named as A to H. Due to the problems with classical biozonations and substages in northern England as well as Belgium and northern France, the biozones established herein are mostly compared with the Russian standard substages. Thus, biozones A and B are correlated with the Mikhailovian, corresponding to the latest Asbian and earliest Brigantian in western Europe; biozones C, D and E are correlated with the Venevian, equivalent to the upper part of the early Brigantian in western Europe. Therefore, biozones A–E form part of the late and latest Viséan. The stratigraphically younger biozones F, G and H contain foraminiferal assemblages correlated with the Tarusian, Steshevian and Protvian, respectively.Fieldwork of D.V. and P.C. was funded by the Spanish Ministerio de Economía y Competitividad (research project CGL2012-30922BTE).Peer reviewe

A mid-Tournaisian-late Viséan carbonate ramp reconstructed from nappes and olistolites in the southern Montagne Noire (France)

The mainly calcareous succession from the mid Tournaisian to the lower part of the upper Viséan in the Southern Montagne Noire Mont Peyroux nappes and Cabrières slices is sedimentologically revised. From the late Viséan, the Variscan orogeny affected the area, and the studied Mississippian part of the succession was considered as part (together with the Devonian) of a period of tectonic quiescence, later included as nappes and olistolites in a wildflysch. This study presents the facies from pelagic limestones, calciturbidites, bioclastic limestones and microbial limestones, and the relationship between platform and calciturbidites in the pre-orogenic context of the Montagne Noire basin during the Mississippian. The differences in the lithostratigraphy is analyzed by means of four tectonostratigraphical units (Mont Peyroux nappe, Roquessels band, Cabrières area and La Serre band) previously defined by other authors, that together with the deep-water Vieussan-Caragnas unit (not studied here due to the poverty in chronostratigraphical data) allow reconstructing the original carbonate platform. The latter seems to correspond to a ramp for the latest Tournaisian to early Viséan, and a distally-steppened ramp from the middle Viséan to the early late Viséan, including basin plain to slope as the deepest water environments, and middle ramp as the shallowest, except for the uppermost part of the succession, where the inner ramp is recognized. During this period, the shallowing tendency in the tectonostratigraphic units is well marked: Mont Peyroux nappe – Roquessels band – Cabrières area – La Serre band (from deeper to shallower), which differs from the shallowing trend defined by previous authors during the Devonian. Strong similarities are observed with the preserved Mississippian carbonates in the Mouthoumet Massif to the south, which might represent the shallowest water deposits of the ramp, not preversed in the Cabrières-La Serre areas.P.C. and I.C. are grateful to the financial support of the Spanish Ministerio de Economía y Competitividad (research project CGL2016-78738).Peer reviewe