甘孜—玉树断裂当江段晚第四纪滑动速率

甘孜—玉树断裂带是青藏高原中东部的一条大型左旋走滑断裂带,同时也是羌塘地体和巴颜喀拉地体的重要地质边界.当江断裂位于甘孜—玉树断裂带的西北段,沿线发育当江荣、当江和哲达等一系列串珠状第四纪断层谷地.通过遥感影像解译和数字高程地形模型(DEM)数据分析,结合野外构造地貌调查,以及断错地貌面的光释光年代测定,发现断裂沿线冲沟、河流阶地和洪积扇等断错地貌发育,反映了该断裂晚第四纪左旋走滑活动性强烈.该断裂最新活动时代为全新世晚期,距今约3.04 ka.当江断裂晚更新世以来的左旋滑动速率为7±3mm·a~(-1).研究结果为该区的地震危险性分析和高原东北部的运动学特征探讨提供了基础资料.

Late Quaternary slip rate of the Garzê-Yushu fault zone (Dangjiang Segment)

Garzê-Yushu fault zone is not only a large-scale left-lateral strike-slip fault in the central-eastern Tibet, but also a significant geological boundary between Bayan Har and Qiangtang blocks. The Dangjiang fault, which is located at the western segment of the Garzê-Yushu fault zone, controls the development of a series of Quaternary fault valleys along it, such as the Dangjiangrong, Dangjiang and Zheda valleys. Based on the interpretation of remote sensing images, analysis of DEM data, field investigations, and optically stimulated luminescence (OSL) measurements, it is found that a series of gullies, fluvial terraces and alluvial fans are systematically offset by the Dangjiang fault, which suggests that the Dangjiang fault is a strongly active left-lateral strike-slip fault in late Quaternary. The time of the latest activity of this fault is after 3.04 ka. Average left-lateral strike-slip rate of this fault is about 7±3 mm·a^-1. This study provides basic materials for the seismic hazard assessment of this area and kinematics analysis of northeastern margin of Tibetan Plateau.