Cenozoic Sedimentology, Stratigraphy and Provenance on the Northern Margin of the Tibetan Plateau: Dahonggou Section, Qaidam Basin, Qinghai Province, PRC

Meredith Anne Bush
The University of Texas at Austin, Jackson School of the Geosciences Austin, Texas, United States of America
[email protected]

The Qaidam Basin is a Cenozoic intra-continental basin on the northeastern margin of the Tibetan-Qinghai Plateau. The modern basin is bounded by the Qilian Shan and Qimentagh-East Kunlun fold-thrust belts to the north and south respectively, and the Altyn Tagh strike-slip fault to the northwest. This project focuses on the Cenozoic basin fill, seeking to link the depositional environments, provenance and chronology of the Qaidam Basin to the regional tectonic history.

High-resolution stratigraphy at the Dahonggou section, consisting of >6 km of fluvio-lacustrine deposits, shows a numerous phases of tectonism and quiescence since the Paleocene. Synorogenic conglomeratic facies are interspersed with fine-grained facies, preserving extensive well-developed paleosol deposits as well as thick channel-sands. Petrographic analysis, outcrop observations of paleoflow direction and clast composition reveal a switch from northeast-directed drainage systems in the base of the section to southwest-directed drainage systems in the upper parts of the section. Specific source areas will be identified from detrital samples collected for zircon U-Pb provenance analysis. Magnetostratigraphy of the complete Cenozoic section will provide the chronology and allow for a tectonic interpretation of the sedimentological data collected in the field.

The results of this study will provide important constraints on the paleogeography of the Qaidam Basin, the topographic growth of surrounding ranges, and the mechanisms of subsidence that are a consequence of the continued India-Eurasia collision.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects