哀牢山—红河构造带古新世以来多期活动的构造和年代学证据  

STRUCTURAL AND DEFORMATIONAL CHARACTERISTICS OF STRIKE-SLIPPINGS ALONG THE MIDDLE-SOUTHERN SECTOR OF THE TAN-LU FAULT ZONE

作　　者：张进江[1] 钟大赉[2] 桑海清[2] 周勇[2] 

机构地区：[1]北京大学地球与空间科学学院教育部造山带与地壳演化重点实验室,北京100871 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《地质科学》2006年第2期291-310,i0005,i0006,共22页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目(批准号:40172074;49802020和49732100);高等学校全国优秀博士学位论文作者专项资金(200022)成果。

摘　　要：哀牢山—红河构造带哀牢山段可划分为东部高级变质带和西部低级变质带。构造分析表明：该构造带由3个不同变形域组成，可能代表其经历的3期左行走滑。第1期走滑发生在整个高级变质带，为拉张性左行走滑，形成角闪岩相L型构造岩。第2期走滑形成高级变质带中的高应变带，变形体制接近简单剪切，形成绿片岩相L-S型糜棱岩。第3期主要发生在低级变质带，为挤压性走滑，形成左行逆冲构造格局，并形成低绿片岩相干糜岩。地质年代学数据证明，3期左行走滑的形成时代分别是：距今58～56Ma、27～22Ma和13～12Ma±。哀牢山—红河构造带第1期左行走滑可能对应于印度与欧亚大陆距今60Ma左右的初始碰撞；第2期变形与青藏高原最强的挤压隆升期一致；第3期事件可能代表距今16～13Ma开始的青藏高原物质进一步东挤。哀牢山—红河构造带的3期主要左行走滑均发生在新生代印度与欧亚大陆的汇聚过程中。Structural analyses showed that the Ailao Shan sector, Ailao Shan-Red River shear zone （ASRR SZ） was composed of three different deformational domains. These domains might represent three episodes of left-lateral slip experienced by the ASRR SZ. The first episode of such deformation occurred throughout the eastern high-grade belt of the ASRR SZ under a transtensional regime and produced L tectonites of amphibolite grade. The second episode of leftlateral slip formed high strain zones overprinting the high-grade metamorphic belt. Its deformational mechanism was similar to simple shear and the deformed rocks were L-S mylonites of greenschist grade. The third episode of left-lateral slip took place chiefly in a western lowergrade belt of the ASRR SZ. This deformation occurred in a transpressional regime, formed an overall structure pattern of a sinistral thrust system and produced phyllonites of lower-greenschist grade. The geochronological data indicated that the three episodes of left-lateral slip happened 58 ～56 Ma ago, at least from ～27 Ma to 22 Ma ago and 13 ～ 12 Ma ago respectively. The first episode of slip in the ASRR SZ appeared to correspond to the initial collision of India and Asia about 60 Ma ago. The second episode took place almost at the same time as the most intensive compression and uplift in Tibet. The latest event might represent a further eastward material flow in Tibet 16 ～ 13 Ma ago. Thus, the ASRR SZ of southeastern Asia probably experienced three main episodes of left-lateral slip since Paleocene in the course of intracontinental convergence by the India-Asia collision.

关 键 词：哀牢山—红河构造带 东南亚 变形历史 地质年代学 印度与欧亚大陆碰撞 

分 类 号：P542[天文地球—构造地质学]