新疆博罗可努—阿齐克库都克断裂精河段古地震与最新活动时代研究

博罗可努—阿齐克库都克断裂是西天山北西向右旋走滑断裂系中最北端的一条活动断裂，其在中国境内延伸最长。本文在艾比湖西侧及精河县东南侧最新地表形变上开挖两条探槽，进行该断裂古地震的初步研究。根据活动性质差异和断裂截切关系将该断裂分为艾比湖段和精河以东段，在对沉积物光释光年代和地震关系分析的基础上，确定了此两段断裂的最新活动时代均为全新世，初步确定其古地震期次，最新地震事件距今3.7—4.86 ka之间；根据冲沟位错和洪积扇年代测定结果，确定精河以东段的活动速率大于4 mm/a；根据探槽错动至地表，及地表破裂带位置及长度，推测艾比湖段可能为1765年精河M61/2的发震构造，且其震级很有可能被低估，因为艾比湖段的破裂总长度超过60 km，震级极有可能达到M7.0以上。

Paleoearthquakes and the latest active age of Jinghe segment of Bolokenu-Aqikekuduk fault

Bolokenu-Aqikekuduk fault is located at the northernmost end of the NW-trending dextral strike-slip fault system in the west Tianshan mountain, and is also the longest active fault extending in China. The latest active ages of both faults are determined to be Holocene based on the relation between the optically stimulated luminescence age of sediments and earthquake colluvial wedges. In this paper, two trenches were excavated on the latest surface deformation in the west of Aibi lake and southeast of Jinghe county. According to activity difference, the fault can be divided into the Aibi lake segment and the east Jinghe segment. The results show that the latest active times of the two segments are determined to be Holocene, and the latest earthquake events occurred on 3.7?4.86 ka BP respectively. According to the results of gully dislocation and pluvial fan dating, the activity rate in the east Jinghe segment is more than 4 mm/a. Furthermore, it is deduced that the Aibi Lake segment may be the seismogenic structure of M61/₂ Jinghe earthquake in 1765, and its magnitude is likely to be underestimated. According to the rupture length of Aibi lake segment more than 60 km, the magnitude is likely to be more than M7.0.