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丽江-小金河断裂是川滇菱形块体内部的一条重要活动断裂,它将川滇菱形块体一分为二,成为陆块内一条重要的横向活动构造带。通过地质学和现今地壳形变观测的方法,获得的丽江-小金河断裂活动速率均在3~5mm/a左右,属于活动强烈的活动断裂。并且该区域破坏性地震频发,本文通过古地震探槽的开挖,对丽江-小金河断裂南段的古地震进行分析,并结合历史地震记录,得到了几点认识:①全新世以来,丽江-小金河断裂南段发生了至少三次古地震事件,分别发生在6540±100 cal yr BP至5420±160 cal yr BP之间、2770±40 cal yr BP至770±100 cal yr BP之间,以及最新地震时间晚于770±100 cal yr BP。②探槽揭露的最新一次古地震事件很可能为历史地震记录的1751年5月25日剑川63/4级地震。
The Lijiang-Xiaoganhe fault is an important active fault in the interior of the rhombic block of Sichuan and Yunnan. It divides the Sichuan-Yunnan rhombic block into two and becomes an important lateral active tectonic belt in the block. Through the methods of geology and present crustal deformation observation, the Lijiang-Xiaojinhe fault movement rate is about 3 ~ 5mm / a, which belongs to a highly active active fault. And the devastating earthquakes in the area are frequent, this paper analyzes the paleoearthquakes in the southern section of Lijiang-Xiaojinhe fault through the excavation of paleoseismic trenches and combines with the historical seismograms to get some recognition: ① Since the Holocene, At least three paleoearthquakes occurred in the southern segment of Lijiang-Xiaojinhe fault at 6540 ± 100 cal yr BP to 5420 ± 160 cal yr BP and 2770 ± 40 cal yr BP to 770 ± 100 cal yr BP, respectively, And the latest seismic time is later than 770 ± 100 cal yr BP. (2) The latest paleo-seismic event revealed by the trenches is likely to be a historical seismic record of the Jianchuan 63/4 May 25, 1751 earthquake.