青藏高原东北缘新近纪晚期构造挤出:来自西秦岭地区安化—成县盆地的证据  

The tectonic extrusion of NE Tibet in late Neogene time: Evidence from Anhua-Chengxian Basin in West Qinling

作　　者：马收先[1] 张岳桥[1] 李海龙[1] 李建华[1] 李勇[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081

出　　处：《地学前缘》2013年第4期58-74,共17页Earth Science Frontiers

基　　金：中国地质调查局项目(1212011120167;1212011120100)

摘　　要：西秦岭位于青藏高原东北缘由挤压走滑向走滑伸展构造的转换地带,成为研究青藏高原晚新生代构造扩展过程的重要构造部位。在西秦岭地区发育的一系列新近纪盆地作为高原物质向外扩展的载体,记录了扩展过程中不同阶段的构造活动和演化信息。文中选择位于成县—太白山断裂内的安化—成县盆地,通过对该盆地沉积过程与构造变形方面的详细研究,确定了盆地在新近纪晚期的两阶段构造演化历史。早期受迭部—白龙江、成县—太白山弧形断裂左行走滑的影响,在弧顶及以东位置发生走滑伸展,形成长条形的地堑半地堑盆地。同期沿青川断裂、西秦岭北缘断裂、礼县—罗家堡断裂以及西和断裂分别形成了汉中盆地、武山盆地、天水盆地以及西和盆地。这些走滑断裂向东扩展可能控制了渭河地堑约9 Ma以来的NW SE向伸展,并伴随华山、太白山以及西秦岭东段10～4Ma的快速隆升。在4.2～2.5Ma期间,受断裂运动学调整的影响,西秦岭地区新近纪盆地遭受挤压而发生构造反转。新近纪盆地的形成与反转历史清楚地记录了青藏高原东北缘新近纪晚期向东构造挤出的过程。West Qinling is located at the tectonic transition from transpression to transtension in NE Tibet,and thus it is a key locality for understanding the outgrowth of the Tibetan Plateau in the late Cenozoic.As a consequence of the northeastward expansion of NE Tibet,the Neogene basins developed along West Qinling recorded the information of this tectonic outgrowth.In this paper,we chose the Anhua-Chengxian Basin as an example for detailed analysis of the sedimentation and tectonic deformation.A two-stage tectonic evolution history was distinguished for this Neogene basin.During the early stage at 10-4 Ma,transtensional sinistral strike-slip occurred along the Diebu-Bailongjiang-Chengxian-Taibaishan fault resulting in the formation of the Anhua-Chengxian Basin.At the same time other basins such as the Hanzhong,Wushan,Tianshui and Xihe basins were initiated respectively along the Qingchuan fault,the northern Qinling fault,the Lixian-Luojiabao fault and the Xihe fault.These strike-slip faults might have propagated eastward and controlled the NW-SE extension in the Weihe graben at 10-4 Ma and fast uplift of the Mts.Huashan and Taibaishan along the southern margin of the Weihe graben.During the time span of 4.2-2.5 Ma,due to the kinematic adjustment of the regional tectonics stress field,the Neogene basins in West Qinling were tectonically inverted by NE-SW compression.Thus,the formation and deformation of Neogene basins in West Qinling obviously recorded the process of tectonic extrusion of NE Tibet in the late Neogene.

关 键 词：安化—成县盆地 沉积过程 构造挤出 青藏高原东北缘 

分 类 号：P542[天文地球—构造地质学]