--> Abstract: Cenozoic Stratigraphy and Structural Style in the Qaidam Basin, Northwest China, and Their Relationship with Regional Tectonics, by Yongtai Yang, Tianguang Xu, Qun Luo, and Quanjun Guan; #90039 (2005)

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Cenozoic Stratigraphy and Structural Style in the Qaidam Basin, Northwest China, and Their Relationship with Regional Tectonics

Yongtai Yang1, Tianguang Xu2, Qun Luo3, and Quanjun Guan4
1 University of Toronto, Toronto, ON
2 IHS Energy, Houston, TX
3 University of Petroleum, Beijing, China
4 Research Institute of Exploration and Development of Qinghai Oilfield Company, Dunhuang, China

The Qaidam basin, situated on the NE Tibetan plateau, has received a great deal of attention as an important petroliferous basin and as an excellent modern example of how the Tibetan plateau formed. However, limited publications and contradictory conclusions on the Cenozoic stratigraphy and structural geology in the basin hinder our understanding of its unique geology in depth. Based on seismic and drilling data, this study attempts to clarify the relationship among regional tectonics, sedimentation and structural style in the basin during the Cenozoic. During the Eocene-Oligocene, the surrounding mountain ranges were uplifted as a result of the India-Asia collision, and the topographic loading led to large-scale subsidence in the western basin where extensive deep lacustrine facies were developed. A series of syn-depositional reverse faults were formed in the basin, resulting in the weak deformation of the Paleogene strata. During the Pliocene-Quaternary, due to the rapid northeasterly propagation of the Altyn Tagh Fault caused by the northward convergence of the India into Asia, relatively intense structural deformation occurred in the basin and from west to east the deformation became gradually weaker and younger. In the western basin, shallow thrust faults were developed in the southern and northern margins and several rows of symmetric folds, bounded by high-angle reverse faults, were formed in the interior of the basin. Strong folding and deformation in the western basin inhibited continued subsidence, thus resulting in the migration of the depocenter to the eastern basin where the thick Quaternary deep lacustrine mudstones were deposited.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005