Reconstructing Cenozoic paleoenvironment in the Xining Basin northeastern Tibetan Plateau
Abstract
The northeastern Tibetan Plateau is characterized by a series of parallel mountain ranges separated by sedimentary basins. The surface uplift in the plateau altered the depositional environment throughout the Cenozoic, prior to the collision between the Indian and Asian plates. But, the paleoenvironmental evolution of the sedimentary basins in the region is poorly understood. In this regard, a detailed field work has been carried out in the Xining Basin which is well known for the development of long continuous Cenozoic sedimentary succession among the entire northeastern Tibetan Plateau. Here, this study examined detailed sedimentary facies analysis through 826 m thick Cenozoic sedimentary successions of the basin together with grain size and petrographic analysis. A total 32 different lithofacies have been identified and grouped into five facies associations: fluvial channel, shallow lake, saline lake, floodplain and fluvio-lacustrine facies. From these sedimentary records, the paleoenvironmental evolution of the Xining Basin underwent five stages. In stage 1, the Xining Basin started to form ( 52-50 Ma) and sediments were deposited in braided fluvial environment. In stage 2, the Xining Basin was an expanded shallow lake during 50-41.5 Ma and sediments were deposited under humid climatic condition. In stage 3, the basin became a persistence playa lake basin between 41.5 Ma and 33.3 Ma and sedimentation took place under repetitive wet-dry cycles. In stage 4, the lake shrunk significantly and sediments were deposited in a floodplain environment during 33.3-25.5 Ma. Finally, in stage 5, rapid deformation in the northeastern Tibetan Plateau changed the depositional environment from lacustrine to fluvio-lacustrine environment during 25.5-16 Ma. The detailed record of sedimentary facies fluctuation with concurrent depositional environment changes of this study will help understand and provide link to the global climate change and uplift history in the northeastern Tibetan Plateau. Keywords: Facies analysis, paleoenvironment, Cenozoic, Xining Basin, Tibetan Plateau.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.T42B..08S
- Keywords:
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- 3355 Regional modeling;
- ATMOSPHERIC PROCESSES;
- 8110 Continental tectonics: general;
- TECTONOPHYSICS;
- 8177 Tectonics and climatic interactions;
- TECTONOPHYSICS