基于河流地貌对祁连山北缘西段地壳活动性的研究-华南地震

文章信息/Info

Title:: The Research of Crustal Activity in the Western Segment of the Northern Margin of the Qilian Mountains Based on River Geomorphology

作者:: 陈志丹1; 2; 刘睿1; 张世民1; 李安1; Koronovskii N.V.2; 1. 中国地震局地壳应力研究所，北京 100085；2. Lomonosov Moscow State University，Russia 119234

Author(s):: CHEN Zhidan1; 2; LIU Rui1; ZHANG Shimin1; LI An1; Koronovskii N.V.2; 1. Institute of Crustal Dynamics，China Earthquake Administration，Beijing 100085，China；2. Lomonosov Moscow State University，Moscow 119234，Russia

Keywords:: The northern margin of Qilian Mountains; River terraces; Tectonic deformation; Active fault

摘要:: 祁连山是青藏高原的东北边界，它既吸收了青藏高原东北方向的地壳挤压缩短，也协调了阿尔金断裂带的左旋走滑分量。祁连山北缘西段的河流地貌特征显示，晚更新世以来北祁连山的隆升作用较为强烈。基于对活动断裂带附近阶地面的高程测量和年代测定，估算了北祁连山山前的玉门断裂64 ka以来的垂直滑移速率为0.33±0.02 mm/a，水平缩短速率为0.53±0.03 mm/a。结合前人数据并对比发现，祁连山北缘断裂带的活动区域正逐渐向北扩展，且其主要活动范围已由原来的主边界断裂带转移到山前的新生断裂及其相关褶皱带中。在祁连山北缘西段，祁连山北缘断裂带所承担的地壳缩短要大于祁连山内部的昌马断裂，这也进一步反映了晚更新世以来北祁连山的地壳挤压活动强度要大于中祁连山。

Abstract:: The Qilian Mountains, as the northeastern margin of the Tibetan Plateau, not only absorbed the northeastern crustal shortening of the Tibetan Plateau, but also transformed the left-lateral strike-slip component of the Altun Tagh fault zone. The river geomorphology in the western segment of the northern margin of the Qilian Mountains shows that the uplift of the northern Qilian Mountains has been much strong since the late Pleistocene. Based on the height measurement and age constraint of the Baiyang River terraces in the western segment of the northern margin of the Qilian Mountains，the vertical slip rate of the Yumen fault is estimated to be 0.33±0.02 mm/a and its horizontal shortening rate is 0.53±0.03 mm/a. The active areas of the northern margin of the Qilian Mountains have been gradually expanding towards the north and its main active region has been transferred from the original main boundary fault to the newly generated fault and its relative fold belt in the piedmont. The result reflects that, in the western segment of the northern margin of the Qilian Mountains, the crustal shortening absorbed by the Qilian Mountains northern fault zone is much faster than that by the Changma fault, which further demonstrated that the compressive crustal activity of the northern Qilian Mountains is intenser than the middle Qilian Mountains since the late Pleistocene.