摘要
在卫星遥感图像的详细地质解译分析基础上,结合野外地质与地貌观察,对帕米尔东北缘山前与印度-亚欧大陆碰撞相关的活动断层进行了分析.研究结果指出,NW-NWW走向的断层主要表现为南倾逆冲断层,并伴随有强烈的右旋走滑分量.流经活动断层带的水系显示出右旋累积位错:小水系的水平位错量为4.0～20.0 m,大河流的水平位错量达8～12 km.沿断层带的上新世至早更新世地层也显示出一致的水平位错,位错量为8～12 km.这些证据表明,帕米尔东南山前的NW—NWW走向的断层很可能开始于上新世末期至早更新世早期(2.2～Ma).研究结果首次厘定了帕米尔东北缘山前与向北逆冲州伴随的右旋走滑速率在第四纪期间达4.0～6.8 mm/a.根据与现代地震活动相关的活断层分析,推测帕米尔东北缘山前7级以上地震重复周期为1 000 a左右.
Based on the detailed geologic mapping and analyses of satellite imagery combining with the field geologic and geomorphic observations, active faults due to India-Eurasia collision have been documented in the northeastern front of the Pamir. Our analyses indicate that NW-NWW striking faults are mainly expressed by the south-dipping thrusting with extensive right-lateral strike-slip component. Drainage systems across the active faults show the cumulative right-lateral displacement and horizontal offset varying from 4.0 m to 20.4 m for small streams. The displaced largest stream and Tertiary to lower Pleistocene sequences show identical horizontal displacement of 8-12 km along the fault zone. Our results firstly constrain that northward overthrusting accommodates a right-lateral partitioning with a long-term slip rate of 4.0-6.8 mm/yr in the northeastern front of the Pamir during Quaternary. From the analysis of active faults associated with current seismic events, we inferred that recurrence interval of large seismic events (Ms >7) is ca. 1 kyr.
出处
《新疆地质》
CAS
CSCD
2003年第1期1-8,共8页
Xinjiang Geology
基金
日本文部科学省基础科学研究项目<中国藏北及天山活动构造>资助
