Integrated stratigraphy of a continental Pliensbachian–Toarcian Boundary (Lower Jurassic) section at Taskomirsay, Leontiev Graben, southwest Kazakhstan
Published:January 01, 2017
Johann Schnyder, Denise Pons, Johan Yans, Romain Tramoy, Saya Abdulanova, 2017. "Integrated stratigraphy of a continental Pliensbachian–Toarcian Boundary (Lower Jurassic) section at Taskomirsay, Leontiev Graben, southwest Kazakhstan", Geological Evolution of Central Asian Basins and the Western Tien Shan Range, M.-F Brunet, T. McCann, E. R. Sobel
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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
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Geological Evolution of Central Asian Basins and the Western Tien Shan Range
The geological evolution of Central Asia commenced with the formation of a complex Precambrian–Palaeozoic orogen. Cimmerian blocks were then accreted to the southern margin in the Mesozoic, leading to tectonic reactivation of older structures and discrete episodes of basin formation. The Indian and Arabian blocks collided with Asia in the Cenozoic, leading to renewed structural reactivation, intracontinental deformation and basin development.
This complex evolution resulted in the present-day setting of an elongated Tien Shan range flanked by large Mesozoic–Cenozoic sedimentary basins with smaller intramontane basins distributed within the range.
This volume presents multidisciplinary results and reviews from research groups in Europe and Central Asia that focus on the western part of the Tien Shan and some of the adjacent large sedimentary basins. These works elucidate the Late Palaeozoic–Cenozoic tectono-sedimentary evolution of the area. Emphasis is given to the collision of terranes and continents and the ensuing fault reactivations. The impact of climatic changes on sedimentation is also examined.