金沙江涛源盆地构造现象研究

Research on Tectonic Phenomena of Taoyuan Basin in the Jinsha River

通过对金沙江涛源盆地东缘断裂活动性的调查和探测,在该盆地内发现许多有地震地质意义的构造现象。分析显示:涛源盆地东缘的金沙江河谷断裂是由一组晚更新世以来活动的铲式正断层组成,以粘滑为主,距今大约4.5万年以来的垂直活动速率为0.6 mm/a;盆地内的NW—NWW向断层是一组与金沙江河谷断裂共轭活动的正断层,距今2.2～4.4万年发生过一次7级左右的地震位错事件;程海—宾川断裂中段的潜在震源区震级上限宜取7.5级。

Through investigating and detecting the activity of faults in the east margin of the Taoyuan basin,some structure phenomena with seismic geological significance have been discovered. The analyze results show that the Jinsha River Valley faults on the eastern margin of the Taoyuan basin are composed of a group of listric normal faults with stick slip mainly since late-Pleistocene,and its vertical movement rate was 0.6 mm/a since about 45 ka.The NW-NWW strike faults in the basin are a group of normal faults conjugate with the Jinsha River Valley fault,and an earthquake about M 7 occurred between 22 ka and 44 ka. The upper limit of the magnitude of the potential earthquake source in the middle section of the Chenghai-Binchuan faults should be taken as 7.5.