塔里木盆地阿瓦提凹陷周缘的晚新生代张扭性断层带

The Late Cenozoic tensor-shear fault zones around Awati Sag,NW Tarim Basin

塔里木盆地西北部的阿瓦提凹陷周缘发育晚新生代正断层,其中第四纪的正断层活动是塔里木盆地构造地质研究的新发现。这些正断层受先存基底断裂控制,平面上沿沙井子断裂带、阿恰断裂带和吐木休克断裂带右阶式雁列状分布,构成右阶左旋张扭性正断层带。剖面上,向下断达下古生界后不清楚,向上断至第四系上部,构成阶梯状或小型地堑(或负花状构造)构造。生长系数计算结果表明,正断层带形成于新近纪末,第四纪早-中期持续活动,到第四纪晚期停止活动。这些张扭性正断层带的成因是阿瓦提地块相对于周边地质体的顺时针旋转而致,其动力学来源于印度板块与欧亚板块陆一陆碰撞,在晚喜马拉雅山期依然持续作用而导致的远程效应。

Late Cenozoic normal faults are developed around Awati Sag,NW Tarim Basin. In which, the Quaternary normal fault activities is the first discovery of structural study in Tarim Basin. The normal faults are controlled with the pre-existed basement faults. Horizontally, they are arranged in right-step en echelon along Shajingzi, Aqia and Tumuxiuke Fault zones, constitute sinistral tenso-shear fault zones. In profile,the normal fault zones cut thxough Upper Paleozoic to Middle Quaternary, forming small horst-graben structures or step cross sections. They not clear in Lower Paleozoic. On the basis of careful seismic interpretation and the growth-indices of the normal faults, the tenso-shear normal fault zones were formed at the end of Neogene, activing in Early-Middle Quaternary and ceased in Late Quaternary. The genesis of the tenso- shear fault zones is the clockwise rotation of Awati block related to its surrounding geologic bodies.