0000000000169979
AUTHOR
Raphaël Bourillot
Architecture and corals ecology of Tortonian-Messinian shallow-water bioherms (Las Negras basin, SE Spain).
International audience
Early–middle Jurassic lytoceratid ammonites with constrictions from Morocco: palaeobiogeographical and evolutionary implications.
13 pages; International audience; The ammonite genus Alocolytoceras Hyatt, 1900 is an uncommon lytoceratid with distinctive shell ornament. A set of 58 specimens, recently collected at Amellago in the central High Atlas (Morocco), has enabled us to trace a succession of three species over eight biozones from the Toarcian to the Aalenian. Two specimens from the Lusitanian Basin are added for comparison. Following a review of the genus, based on original specimens and data from the literature, seven species are considered valid. A palaeobiogeographical synthesis of 13 regions demonstrates irregular distribution patterns over time, with a constant presence in the south-west Tethys and an insta…
Formation of microbial organic carbonates during the Middle Oxfordian (North East Amu Darya Basin, Uzbekistan): palaeoenvironmental significance and implications for Jurassic anoxic events
International audience; The Late Jurassic was a period of major global carbon cycle perturbations with episodes of anoxia leading to regional accumulation of organic matter in sediments worldwide. The Tubegatan section (SW Gissar Mountains, Uzbekistan) located in the Northern Tethys, shows atypical organic-rich limestone and marl deposits (up to 6% of total organic carbon) marked by pronounced excursions of δ13Ccarb (amplitude of ca. 12‰) and δ13Corg (amplitude of ca. 4‰) recorded during the Middle Oxfordian (Transversarium Zone). A transdisciplinary approach including sedimentology, palynofacies study, mineralogy, organic and inorganic geochemistry was carried out to elucidate the origin o…
The end of the Messinian Salinity Crisis in the western Mediterranean: insights from the carbonate platforms of south-eastern Spain.
International audience; How the Messinian Salinity Crisis (MSC) ended is still a matter of intense debate. The Terminal Carbonate Complex (TCC) is a late Messinian carbonate platform system that recorded western Mediterranean hydrological changes from the final stages of evaporite deposition till the advent of Lago-Mare fresh- to brackish water conditions at the very end of Messinian times. A multidisciplinary study has been carried out in three localities in south-eastern Spain to reconstruct the history of TCC platforms and elucidate their significance in the MSC. Overall, this study provides evidence that the TCC formed following a regional 4th order water level rise and fall concomitant…
Stratigraphic modelling of platform architecture and carbonate production: a Messinian case study (Sorbas Basin, SE Spain).
27 pages; International audience; The late Messinian mixed carbonate-siliciclastic platforms of the Sorbas Basin, known as the Terminal Carbonate Complex, record significant changes in carbonate production and geometry. Their facies and stratigraphic architecture result from complex interactions between base-level fluctuations, evaporite deformation/dissolution and detrital inputs. A 3D quantitative approach (with DIONISOS software) is used to explore the basin-scale platform architecture and to quantify the carbonate production of the Terminal Carbonate Complex. The modelling strategy consists in integrating detailed 2D field-based transects and modern carbonate system parameters (e.g. car…
Structure and evolution of the Gissar carbonate platform (Uzbekistan): a record of palaeoenvironmental changes in the Northern Tethys margin during the Middle and Late Jurassic
International audience; The SW-Gissar range (westernmost part of the Tien Shan) consists of a succession of anticlines andsynclines forming a relief between the Amu Darya and Afghan-Tajik basins. Recent fieldwork has beenperformed to study the development and the architecture of a vast Middle-Upper Jurassic carbonate platform. The studied carbonate series crops out along cliffs overlying Lower to Middle Jurassic continental then marine deposits. Carbonate thickness reaches 500 m in the central and southern Gissar and thins up northwards, near the paleo-border of the Amu Darya Basin. The goal of this study was to build a highresolution stratigraphic framework for these deposits, based on che…
Structure and evolution of a Messinian mixed carbonate-siliciclastic platform: the role of evaporites (Sorbas Basin, South-east Spain).
36 pages; International audience; The Sorbas Member is a late Messinian complex sedimentary systemthat formed immediately following deposition of the Messinian evaporites in the Sorbas Basin (South-east Spain). This work describes the sequence architecture and facies organization of a continuous kilometre long, alluvial fan to open platform transect near the village of Cariatiz in the north-east of the basin. The postevaporitic Cariatiz platform was a mixed carbonate-siliciclastic system composed of four intermediate-frequency, fifth-order depositional sequences (Depositional Sequences 1 to 4) arranged in an overall prograding trend. The intense fracturing and brecciation of these deposits …
Characterization of Upper Jurassic organic-matter-rich carbonates in the Gissar Mountains (Tubiegatan section, Uzbekistan)
International audience; New investigations are currently underway on the Middle-Upper Jurassic carbonates of the Gissar Mountains in the Amu-Darya Basin. Located in the southwest of the Gissar Mountains (SE Uzbekistan), the Tubiegatan section corresponds to 30-meter-thick limestone, overlain by 10-meter-thick dark limestone and marl interval. These dark, “black shale-type deposits” were also recognized in cores from the subsurface of the Amu-Darya Basin. The organic-rich deposits interval is precisely dated to the Luciaeformis and Schilli Subzones (Transversarium Zone, Middle Oxfordian) by ammonites. A transdisciplinary approach including sedimentology, organic matter characterization (Rock…
The stratigraphic record of the Middle-Late Jurassic Transition events on the Peri-Tethyan carbonate platforms
The Middle and Upper Jurassic peri-Tethyan carbonate platforms host some of the largest hydrocarbon reserves in the world. Over the past decades, extensive research has led to the construction of high-resolution stratigraphic frameworks on the northwestern (e.g., Paris Basin) and southern (e.g., Arabian Platform) Tethyan margins. These studies and others show that although being a period of elevated carbonate production, the Callovian-Oxfordian interval is marked by major changes in carbonate production and platform architecture, stratigraphic gaps and condensed series. These changes have commonly been linked to regional to global climatic and tectonic events associated with the so-called M…
The role of topography and erosion in the development and architecture of shallow-water coral bioherms (Tortonian-Messinian, Cabo de Gata, SE Spain).
23 pages; International audience; During the Miocene, Mediterranean shallow-water carbonates were rich in scleractinian corals, which thrive in various depositional settings. A Tortonian–Messinian bioherm belt developing in a heterozoan-dominated ramp was investigated along a 1.2 km continuous transect located in the Cabo de Gata region. The interval studied displays four depositional environments from mid-to-inner ramp, dominated by swell waves and storm energy, deposited as a single, large-scale depositional sequence during a 3rd to 4th order transgressive–regressive cycle. The bioherms grew in three phases, and were essentially composed of inplace primary frameworks. Three coral genera w…
Morphometry of micrite particles in cretaceous microporous limestones of the Middle East: influence on reservoir properties.
24 pages; International audience; Microporosity may account for a significant part of the total porosity of Cretaceous limestone reservoirs of the Middle East. In these microporous facies porosity is moderate to excellent (up to 35%) while permeability is poor to moderate (up to 190 mD). Micritic limestones also may form dense layers with very low porosity and permeability values. Micritic samples were collected from three fields of the Habshan and Mishrif Formations, to examine the spatial relationship with their porosity, permeability and pore throat radius distributions. Two key parameters of the micritic particles are studied using scanning electron microscopy: their morphology (shape a…
Formation of microbial organic carbonates during the Late Jurassic from the Northern Tethys (Amu Darya Basin, Uzbekistan): implications for Jurassic anoxic events.
23 pages; International audience; The Late Jurassic was a period of major global carbon cycle perturbations with episodes of anoxia leading to regional accumulation of organic matter in sediments worldwide. The Tubiegatan section (SW Gissar Mountains, Uzbekistan) located in the Northern Tethys, shows atypical organic-rich limestone and marl deposits (up to 6% of total organic carbon) marked by pronounced negative excursions of δ13Ccarb (amplitude of ca. 12‰) and δ13Corg (amplitude of ca. 4‰) recorded during the Middle Oxfordian (Transversarium Zone). A transdisciplinary approach including sedimentology, palynofacies characterization, mineralogy, organic and inorganic geochemistry was carrie…
Origine des carbonates organiques de la Formation Khodjaipak (Oxfordien moyen) dans le Nord-Est du Bassin d’Amu-Darya : signature paléoenvironnementale et impacts sur le cycle du carbone
Les reptiles et synapsides fossiles de Bourgogne.
65 pages; National audience; L'inventaire actuel des Amniotes (Synapsida et Reptiles) fossiles à partir des collections bourguignonnes est présenté dans l'ordre stratigraphique. Il montre que les Synapsida (Reptiles Mammaliens) sont représentés au Carbonifère et au Permien inférieur par quelques squelettes. Dans le reste du Permien (moyen ou moyen à supérieur) ) puis au Trias, c'est la palichnofaune qui prend le relai avec quelques empreintes de pas permiennes attribuées à des Capthorinomorpha et avec celles beaucoup plus nombreuses du Trias laissées par une faune très variée. Celle-ci comportait le groupe souche des Crurotarsi d'où sont issus les Crocodylomorpha et les Dinosauria via les D…