Integrated stratigraphy of a continental Pliensbachian–Toarcian Boundary (Lower Jurassic) section at Taskomirsay, Leontiev Graben, southwest Kazakhstan

Abstract

During the Early Jurassic, major palaeoclimatic changes, associated with large carbon-cycle perturbations, occurred at the Pliensbachian–Toarcian boundary. Although the detailed marine palaeoclimatic record of this time interval and its impact on the marine biota is well recorded, much less is known about the continental realm. The current study documents new palynological and high-resolution carbon isotope data measured on bulk organic matter from the continental Lower Jurassic section of Taskomirsay in Kazakhstan, Central Asia. Both datasets allow a transition zone between the Pliensbachian and Toarcian to be identified. In addition, the spore and pollen distribution suggests a warming trend from the Pliensbachian to the Toarcian, most probably associated with a shift in floristic associations from the Siberian to the Sino-European palaeofloristic provinces, as recorded elsewhere in Central Asia during the Early Jurassic. The Taskomirsay section is thus of primary interest for palaeoclimatic studies as it is one of the very few well-dated continental section worldwide that records the Pliensbachian–Toarcian palaeoclimatic changes.Supplementary material: Table of δ13Corg data, Taskomirsay section, Karatau Graben, Kazakhstan is available at https://doi.org/10.6084/m9.figshare.c.3495645

Jurassic paleogeography of the Tian Shan: An evolution driven by far-field tectonics and climate

“…Lower Jurassic sediments have a pre Toarcian age based on palynological and geochemical studies (Schnyder et al,2016) while no clear stratigraphic ages are available for the south Turgay and Yarkand Fergana basins. Geochronological data indicate that the Talas…”

Source-to-sink dynamics in the Kyrgyz Tien Shan from the Jurassic to the Paleogene: Insights from sedimentological and detrital zircon U-Pb analyses

“…It locally contains up to 4500m of non-marine clastic Jurassic sediments. In the Leontiev Graben, the Jurassic sedimentary succession can reach up to ca 2 km (Buvalkin et al, 1991;Sobel, 1999;Schnyder et al, 2016). The Yarkand-Fergana Basin is a transtensional pull-apart basin located along the western side of the TFF in southern Kyrgyzstan and extends southwards into the western Tarim (Burtman et al, 1996;Sobel, 1999;Allen et al, 2001;Alexeiev et al, 2017) (Fig.…”

Geological evolution of Central Asian Basins and the western Tien Shan Range

“…Investigation of the sedimentary successions contained with the basins which formed within the broader Tien Shan orogen thus provide overviews of the Mesozoic (five papers) and Cenozoic (two papers) history across the region, focusing as they do on the interlinkage of sedimentation, tectonics and climate. Schnyder et al (2016) examine palynological and high-resolution carbon isotope data measured on bulk organic matter from the Lower Jurassic continental succession in the Leontiev Graben of Kazakhstan. The two datasets are in agreement, allowing the recognition of the transition zone between the Pliensbachian and the Toarcian.…”

“…In Central Asia, the Mesozoic period was marked by pronounced tectonic activity but also by climatic changes, specifically, the transition from a humid climate during the Middle TriassicMiddle Jurassic to a semi-arid-arid climate through to the Late Jurassic -Early Cretaceous (e.g. Hendrix et al 1992;Shao et al 2003;Cecca et al 2005;Fü rsich et al 2015;Jolivet 2015;Jolivet et al 2015;McCann 2016a, b;Schnyder et al 2016;Brunet et al 2017). Subsequently, during the early Cenozoic regionally well-correlated marine transgressions occurred (Bosboom 2013;Bosboom et al 2015).…”