徐家围子断陷深层构造样式特征的成因机制分析

A Study on the Mechanism of Structural Styles in Deep Layer of Xujiaweizi Fault Depression

徐家围子断陷深层构造复杂,据应力场特征的差异性,可以划分为伸展型构造样式和挤压型构造样式两种类型,前者是在拉张环境的应力场下形成,其成因机制是火石岭期至沙河子期依泽奈崎板块的高速斜向俯冲以及引起的地幔上涌导致地壳减薄拉张而形成,后者是在挤压应力场环境下形成:而挤压应力场是沙河子末期至营城期西太平洋板块的正向俯冲及地幔的热冷却作用导致的。

It exists complicated structures in the deep layer of Xujiaweizi fault depression. According to the different characteristics of the stress field,two structural styles can be divided into:extensional structural style and extrusional structural style.The former forms in the extensional stress field,and the cause of mechanism is Izanaqi plate subduction under continental plates of East Asia at the period of Huoshiling group toShahezi group,with the result that mantle upwelling,the surface of Moho uplifting and lithospheric thinning at the East Asian continental margin,formed extensional stress field of EW-NEE trending in the region;the mechanism of extrusional structure styles is:The subduction of west Pacific plate being transformed the oblique subduction into dive subduction during the end deposition of Shahezi group and Yingcheng group, Xujiaweizi fault depression was in the extrusional stress field environment in the period.