东昆仑断裂带东段玛曲断裂新活动特征及全新世滑动速率研究

Study on characteristics of new activity and Holocene slip rate along Maqu fault of East Kunlun Active Fault

东昆仑活动断裂是青藏高原东北部一条重要的NWW向边界断裂。玛曲断裂位于东昆仑断裂带的最东段。根据野外考察结果认为玛曲断裂全新世以来活动强烈，主要表现为左旋走滑运动，并伴有正倾滑运动性质。断错地貌特征明显，断裂过玛曲县城以后，沿黑河南岸穿过若尔盖草地向东，直至岷山北端求吉附近。通过两处断错地貌的全站仪器实测和测年资料讨论了玛曲断裂新活动特征和全新世滑动速率，玛曲断裂全新世早期以来的平均水平滑动速率为6．29～5．71mm／a，全新世晚期以来的平均水平滑动速率为4．19～4．03mm／a。

The East Kunlun active fault is an important NWW-trending boundary fault on the northeastern margin of the Qinghai-Tibet Plateau. Maqu Fault is the easternmost segment of the East Kunlun active fault. Based on the field investigation, the activity along the Maqu fault since Holocene has been characterized by left-lateral （sinistral） strike-slip and normal slide faulting. The characteristics of dislocation geomorphology are obvious. The fault runs through the Maqu County, and then extends to east along the southern side of Heihe River and through the Ruoergai Grassland, and the end of Maqu fault reaches Qiuji on northern sides of the Minshan Mountain. Moreover, based on measurement of geo- morphologic offset at the two sites by Total Station Instrument and the sample dating, the authors discussed new activity of Maqu fault and slip rate since Holocene. The average rate of horizontal displacement is calculated as 6.29-5.71 mm/a since early stage of Holocene and 4.19-4.03 mm/a since late stage of Holocene, respectively.