Earth Science Frontiers ›› 2020, Vol. 27 ›› Issue (1): 275-286.DOI: 10.13745/j.esf.sf.2020.5.5

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Discussion on the Cenozoic tectonic evolution and dynamics of southern Tibet 

LIU Demin, YANG Weiran, GUO Tieying, RU Jiangtao, XIONG Aimin 
 
  

  1. School of Earth Sciences, China University of Geosciences, Wuhan 430074, China 
     
  • Received:2019-11-01 Revised:2020-05-18 Online:2020-01-20 Published:2020-12-30
  • About author:Dr. Liu Demin (b. 1975) is an associate professor and expert in structural geology. His research mainly focuses on the geodynamics of continental and geothermal geology. E -mail: 5guc@163.com
  • Supported by:
    Hot Dry Rock Resources Survey Projects of Guangxi Province, China (2019016110 and  2019016207), Geological Survey  Projects  of  China  Geological  Survey  (200013000145),  the  National  Natural  Science  Foundation  of  China  (NSFC) 
    Project (41172087 ) 

Abstract:

Opening-closing tectonics is a new idea for exploring the global tectonics, which holds that every tectonic movement of all materials and geological bodies on earth is characterized by opening and closing. The opening -closing tectonic view can be used to explain some geological phenomena developing in continents which cannot be reasonably explained by the theory of plate tectonics. Based on the available basic geological data and combining with the opening-closing view, we analyzed the divisions and characteristics of tectonic units in South Tibet, and propose that Tibet can be divided into gravitational detachment and detachment fault zones, which are superimposed thrust fault zones  and reconstructed normal fault zones, respectively. Although the mainstream opinion believed that the Tibetan Plateau is formed by collision-compression orogenesis, field investigation revealed the existence of the Rongbu Temple normal fault in the1970s. We consider that the Rongbu Temple normal fault and the Main Central Thrust (MCT) were formed earlier than the South Tibet detachment fault, and the former two  faults constitute the two boundaries of the southern Tibet extrusion structure. The South Tibet detachment fault partially superimposes on the MCT and manifests a relatively high angle in following the Rongbu Temple normal fault north of  the Chomolangma. We suggest that the three fault systems are the products of different periods and tectonic backgrounds. The tectonic units, such as klippes and windows identified by previo us researchers in southern Tibet, belong to thrust fault system but usually have no obvious extrusion or  thrust characteristics; however, they are characterized by missing strata columns as younger strata overlapping the older ones. These  klippes and windows should be the results of later gravitational decollement and must be characterized as extensions and slips, respectively. Based on opening-closing theory, we  suggest that since the Cenozoic the study area had undergone multistage development, which  can be divided into the oceanic crust expansion (opening) and subduction (closing) and the continental collision (closing) and intracontinental  extension (opening) stages. Geothermal energy from the deep earth, gravitational potential energy from the earth’s interior, and additional stress energy from tectonic movements, all played a key role in the multistage tectonic evolutionary process. 

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