乌鲁木齐西山逆断层组的新活动特征

Recent Activity Characteristics of the Xishan Fault Group in Urmuqi

通过大比例尺的地质地貌填图工作获得了乌鲁木齐西山逆断层组的几何学特征、新活动和运动速率等相关的定量资料。西山逆断层组由5条长度十几～30余千米、近乎平行的次级断层组成,总体走向NEE,分布在南北宽约6.5km的条带范围内。该断层组南侧的两条断层属于晚更新世活动断层,北侧3条全新世以来仍有活动,其新活动具有分组和组合破裂的特征。西山逆断层组以向南的逆冲运动为主,地表形成了一系列阶地断错、挤压鼓包和断塞塘等新活动现象。根据对断层运动量的测量及年代学测定,获得该断层组中更新世晚期以来所造成的南北向地壳缩短速率为1.0～1.5mm/a,晚更新世晚期以来南北向地壳缩短速率为0.22mm/a左右。

The completion of geography and geology on large proportion maps yields a certain amount of quantitative data of geometric features, new activities and velocity ratio of Xishan Fault in Urmuqi. The fault group consists of 5 secondary faults with different lengths from a dozen meters to over 30000 meters and almost parallel secondary order. The fault group are generally striking NEE, distributed along a strip of 6.5kin in width in north-south direction. The two faults on the south side of the group belong to late Pleistocene and the three faults on the north side have been active since Holocene Epoch. The faults are south-dipping thrust faults and form a series of uneven terrains, upheaval and dam-gradations on land surface. The measurement and chronological determination of fault movements reveal that the average crust shortening rate in SN is 1.0 - 1.5mm/a since middle-Pleistocene, and that of since late-Pleistocene in SN is about 0.22mm/a.