青藏高原东南缘晚新生代川滇地体旋扭构造体系地壳变形特征的古地磁学分析  

The Paleomagneitc Analysis about the Later Cenozoic Crustal Deformation Characteristics of the Chuandian Terrane Clockwise Rotation System in the Southeast Edge of Tibet Plateau

作　　者：仝亚博[1,2] 杨振宇[1,2] 张旭东[3] 吴中海[1] 赵越[1,2] 王恒[1] 徐颖超[1] 高亮[1] 安纯志 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]国土资源部古地磁与古构造重建重点实验室,北京100081 [3]江苏省有色金属华东地质勘查局,南京210007

出　　处：《地质学报》2014年第11期2057-2070,共14页Acta Geologica Sinica

基　　金：中国地质调查项目(编号1212011120164);国家自然科学基金(编号41202162);国家深部探测实验研究专项(编号Sinoprobe08-01-01)联合资助成果

摘　　要：通过对川滇地体、思茅地体白垩纪、古近纪地层古地磁数据以及新生代地壳构造特征的分析,结合青藏高原东南缘GPS监测研究结果,揭示了新生代时期青藏高原东南缘地壳块体的旋转变形特征.根据古地磁数据模拟计算得出～5Ma以来哀牢山-红河走滑断裂带（ARF）受川滇地体挤压而发生弯曲变形的南北向偏移速率至少为～13.05mm/a,奠边俯左旋走滑断裂带（DBPF）西侧思茅地体内部自～5Ma以来至少存在～2.08mm/a的东西向伸展分量,而DBPF 5Ma以来的南北向平均左旋走滑速度则至少为～1.66mm/a,与现今GPS监测结果基本一致.证明鲜水河-小江左旋走滑断裂带（XXF）的左旋走滑运动虽然没有切断ARF,但是川滇地体的南向顺时针旋转挤压作用导致了断裂带的南向弯曲变形,从而吸收了部分左旋走滑速率,造成左旋走滑运动在跨过ARF传递到DBPF后走滑速率发生了突变,由～10mm/a减小于2～3mm/a.缅泰地块和思茅地体在经历了渐新世-中新世时期以高黎贡山-实楷右旋走滑断裂带和ARF为边界的东南侧向顺时针旋转挤出运动之后,自5Ma开始,至少思茅地体与川滇地体一起,以XXF和DBPF为旋转边界发生了以东喜马拉雅构造节为近似中心的旋转挤出运动.The analysis about the Cretaceous and Paleogene paleomagnetic data, the tectonic characteristic and the GPS monitoring of the southeast edge of Tibet Plateau indicates the Cenozoic crustal rotational deformation characteristics of Chuandian Terrane and the east part of Simao Terrane. Paleomagnetic analysis shows that since -5Ma, the middle segment of Ailao-Red River Fault （ARF） experienced southward bending deformation with at least -13.05mm/yr north to south average bending rate. The north to south average sinistral strike slip rate of Dien Bien Phu Fault （DBPF） was at least -4.98mm/yr since -5Ma, meanwhile, at least-6.2mm/yr west to east stretching deformation rate were estimated form the easternmost part of Simao Terrane. The paleomagnetic analysis is consistent with the GPS monitoring result, which shows that although the sinistral strike-slip movement of Xianshuihe-Xiaojiang Fault （XXF） does not cut off the ARF, the clockwise rotational extrusion movement of Chuandian Terrane induced the bending of middle segment of ARF, which absorb part of the slip rate of XXF, and finally result in the suddenly decrease of the sinistral slip rate from XXF to DBPF. In the Oligocene- Miocene time, the Shan-Thai Block experienced clockwise rotational extrusion movement along the Gaoligong-Sagaing Fault and the ARF, since -5Ma, at least the northeast part of Shan-Thai Block and the Chuandian Terrane experienced second stage rotation deformation around the Eastern Himalaya Syntaxis, the XXF and DBPF constitutes the eastern boundary fault of the second stage rotation deformation system which experienced clockwise rotational deformation around the Eastern Himalaya Syntaxis.

关 键 词：川滇地体 思茅地体 白垩纪 鲜水河-小江左旋走滑断裂带 奠边俯左旋走滑断裂带 

分 类 号：P542[天文地球—构造地质学] P318.44[天文地球—地质学]