Sedimentary Filling History and Analysis of Its Controlling Factors in the Paleogene of the Northwestern Qaidam Basin, China

Key words: 
• sedimentary facies

Abstract: Quantitative studies on the Paleogene sedimentary filling history and analysis of its controlling factors were carried out based on studies of topography, sediment provenance, constitution and distribution of sedimentary system in Qaidam basin. Western region of Qaidam basin can be divided into several secondary uplifts and depressions controlled by Cenozoic strikeslip process of Altyn Tagh. In Xiagancaigou depositional stage (about 60~40 Ma), with the fast uplift of Altyn Tagh, several subsidence centers were created in the front zone of Altyn Tagh. Deposition centers were transported from Shizigou to Nanyi mountain and Youquanzi area. It can be divided into two types of sedimentary areas during Xiagancaigou deposition period bounded by Jianding mountainNanyi mountainYouquanzi: (1) proximal deposits of alluvial fanfan deltasublacustrine fansemideep lake depositional systems at the front zone of Arkin mountain; (2) alluvial fanfluvialdeltashoreshallow lacustrine depositional systems at JiandingshanDafengshan ramp zone. Sedimentation of subsidence center at the front zone of Altyn mountain accelerated during Shanggancaigou deposition period, sedimentary facies in this period is mainly shallowlake facies. Affected by reduction of sediment supply by Niubiziliang, lake of Dafengshan region developed easternward and northwestern of Qaidam basin is extensively covered by shallow lacustrine.