Cenozoic Tectonic Evolution of the Western Qaidam Basin and Its Constrain on the Growth of the Northern Tibetan Plateau
详细信息
- 责任者：Wu Chan (State Key Laboratory of Continental Tectonics and Dynamics ; Institute of Geology ; CAGS ; Beijing 100037 ; China) ; Yan Cunfeng
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(6)
- 关键词：构造演化 ; structural evolution ; 柴达木盆地 ; Qaidam Basin
- 页码：p.2211-2222
- 图表：illus., 67 refs.
- 分类号：0300
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Qaidam Basin,a Cenozoic petroliferous basin,lies on the margin of the northern Tibetan Plateau. It records a lot of information about uplift and expansion of the northern Tibetan Plateau. High resolution satellite images,geophysical data and magnetostratigraphy chronology data are used to analyze the mechanism and development of fold belts in the western Qaidam Basin. It reveals that: ( 1) Hongsanhan,Jiandingshan-Heiliangzi,Nanyishan and Youshashan fold belts are all composed of asymmetric vertical or homoclinal folds related to thrusting,of which,just as the Jura-type fold,the tight anticline alternates with gentle syncline, indicating adecollement structure atdepth; (2) Folds with gentle SW limb and sharp NE limb like Hongsanhan and Jiandingshan-Heiliangzi fold belts are formed by northeastward thrusting; the southwestward thrusting creates a fold with sharp SW limb and gentle NE limb,like Youshashan fold; the relative symmetric Nanyishan fold belt results from NW-SE thrusting; (3) The growth strata on the Hongsanhan,Jiandingshan-Heiliangzi and Nanyishan fold belts are Xiaganchaigou,Shizigou and Qigequan formations,with the high-resolution magnetostratigraphic age of ～39. 5Ma,～ 8.2Ma and ～2. 5Ma,respectively. The initial time of growth strata presents the initial formation age of the fold belt as well as the age of thrusting. A series of similardrainage systems on the Youshashan fold belt is bending along the regional tectonic strike. This implies that the ongoing growth is taking placed in the Youshashan region. The SN vertical Hongsanhan fold,along with dome-like superimposed fold in the western Qaidam Basin,indicates a EW compression associated with the strike-slip of the Altyn Tagh fault; (4) Based on the tectonic geomorphology,growth strata,seismic reflection profiles and magnetostratigraphy,the main fold belts in the western Qaidam Basin result from southward propagating during Cenozoic. The backward propagation model indicates that Indian-Asian collision stress has reached the northern part of the Qaidam Basin at ～40Ma,formed the Hongsanhan thrust-fold belt. With the continuous compressing,Jiandingshan,Nanyishan and Youshashan fold belts come into being one by one,ofwhich,the latter two fold belts,the composition of the present " Yingxiongling" ,are formed under the strong S-N compression since ～2. 5Ma. Since～8Ma,the intensive activity of the Altyn Tagh fault had affected the entire Qaidam basin.