0000000001096541
AUTHOR
Marie-françoise Brunet
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…
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…
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…