青藏高原大型走滑断裂带晚新生代构造地貌生长及水系响应  

Late Cenozoic tectono-geomorphic growth and drainage response along the large-scale strike-slip fault system, Tibetan Plateau

作　　者：付碧宏[1] 时丕龙[1] 贾营营[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029

出　　处：《地质科学》2009年第4期1343-1363,共21页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目(编号:40872126);中国科学院知识创新工程重要方向性项目(编号:KZCX2-YW-12)的资助

摘　　要：大型走滑断裂带对调节印度板块和业洲板块碰撞后产生的陆内构造变形和地貌生长起着非常重要作用。本文分析了沿青藏高原北缘主要大型左旋走滑断裂带:东昆仑、康西瓦和鲜水河—小江断裂带发育的错断地质体、大型错断水系或水系拐弯等新构造地貌特征,表明这些大型走滑断裂带在晚新生代以来发生了大规模的左旋走滑运动:前新生代地质体错位距离为80～120 km,大型水系累积的位移量可达80～90 km。根据这些走滑断裂带的长期走滑速率为8～12 mm/a,估算上述大型走滑断裂带的左旋走滑运动开始于中新世晚期:东昆仑和康西瓦断裂带左旋走滑运动开始于10±2 Ma;鲜水河—小江断裂带甘孜—玉树段的左旋走滑运动的开始时间约为11.5～8 Ma。同样,如果大型水系的沿断裂带出现的大型错位或拐弯能够代表断裂带累积错位的上限,表明发源于青藏高原的黄河、金沙江、喀拉喀什河和玉龙喀什河等一级水系上游大致开始形成于9～7 Ma±。西昆仑山前盆地中河流相沉积的最早响应时间为8～6 Ma,与喀拉喀什河和玉龙喀什河等西昆仑山地区一级水系的形成时间基本一致,表明这些大型水系初始形成时间与左旋走滑构造运动的开始时间准同时。这表明中新世中晚期青藏高原构造演化发生了重要转变。The large-scale strike-slip faults play an important role in Cenozoic intraeontinental deformation and geomorphic growth of Tibetan Plateau and adjacent region related to the India- Asia collision. In this study, we document displacement of geologic units and systematic offset streams produced by the left-lateral movements along the East Kunlun, Kangxiwar and Xianshuihe-Xiaojiang faults. Displaced tectono-geomorphic features suggest a sinistrial displacement of 80 - 120 km occurred along these large-scale left-lateral strike-slip fault systems since Cenozoic. Our results indicate that the eastern Kunlun and Kangxiwar fault zones probably began left-lateral faulting at ca. 10±2 Ma based on a total maximum displacement of 105 -120 km,and assuming a constant long-term slip rate of ca. 10 mm/a for several millions of years. Similarly, we inferred that the Xianshuihe-Xiaojiang likely initiated its sinistral slip faulting since 8 - 11.5 Ma,based on a total maximum displacement of 80 km,and assuming a constant long-term slip rate of 7 - 12 mm/yr. Moreover, the first-class stream systems along these strike-slip fault systems appeared 80 -90 km long-term accumulative displacement,which suggest that these stream systems initiated since ca. 8 Ma. The geologic age of fluvial sequence in the piedmont basin of the western Kunlun Range is well consistent with geologic age of formation for these first-class drainage systems in the Tibetan Plateau.

关 键 词：构造地貌生长 走滑断裂带 大型水系 沉积响应 晚中新世 青藏高原 

分 类 号：P542[天文地球—构造地质学]