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四川盆地西北部新生代构造变形模式讨论——对认识青藏高原东北缘新生代变形机制的意义

罗 良,贾 东,李海滨,邓 飞,李一泉,武 龙   

  1. 南京大学 地球科学与工程学院,教育部 含油气盆地构造研究中心,南京 210093
  • 收稿日期:2008-12-20 修回日期:2008-12-20 出版日期:2008-12-20 发布日期:2008-12-20

Cenozoic Deformation of the Northwestern Sichuan Basin——Significance for Understanding the Cenozoic Deformation Regime of the Northeastern Tibetan Plateau

LUO Liang, JIA Dong, LI Hai-bin, DENG Fei, LI Yi-quan, WU Long   

  1. School of Earth Sciences and Engineering, Nanjing University and Research Center for Structures in Oil & Gas Bearing Basins, Ministry of Education,, Nanjing 210093, China
  • Received:2008-12-20 Revised:2008-12-20 Online:2008-12-20 Published:2008-12-20

摘要: 综合造山带内的构造热年代学及盆地内部进行的磷灰石裂变径迹研究,提出了四川盆地西北部的三个背斜(潼梓关背斜、九龙山背斜和南阳坝背斜)主要是新生代构造变形的产物。野外观察发现汉中盆地是一个第四纪的拉分盆地,其主控断层具左行走滑性质。新生代青藏高原东缘大型地块向东挤出,遭遇强硬的四川克拉通阻挡之后,沿着龙门山形成了一个右行的走滑挤压带,并且影响到邻近的四川盆地,形成北东向背斜。这期构造变形往北延伸进入米仓山,形成具有逆冲性质的北东向断层。四川盆地北面也存在向东的挤出作用,这和汉中盆地主控断层的左行走滑性质是匹配的。四川盆地北面的地块挤出影响了米仓山前缘的四川盆地,由于龙门山和米仓山构造变形的叠加,使得最东面的南阳坝背斜相对于其它两个背斜在褶皱轴上发生了偏转。

Abstract: Thermochronology researches in the orogens and apatite fission track analysis in the basin suggest that three NEtrending anticlines (Tongziguan anticline, Jiulongshan anticline and Nanyangba anticline) in the NW margin of the Sichuan Basin were formed in the Cenozoic. Based on the field observation, the Hanzhong Basin to the north of the Sichuan Basin is a Quaternary pull-apart basin, and its major faults are sinistral strike-slip ones. When the large blocks of the eastern Tibetan Plateau extruded eastwards in the Cenozoic and encountered the rigid Sichuan Basin, a transpressional belt was formed along the Longmenshan Mountain. It affected the northwestern Sichuan Basin, resulted in formation of three NE-trending anticlines. It also further extended northeastwards into the Micangshan Mountain, forming several NE-trending reverse faults. The eastward extrusion of the Tibetan Plateau also took place north of Sichuan Basin, which matches with the sinistral strike-slip property of the faults controlling the Hanzhong Basin. The eastwards extrusion of the Tibetan Plateau also affected the arcuate Micangshan Mountain,which led to another SSE-ward deformation affecting the northwestern Sichuan Basin. The deformation superposition induced the deflexing the axis of Nanyangba anticline relative to the other two anticlines.