塔里木盆地库车坳陷西秋古隆起的形成及其演化

重力异常资料显示, 库车坳陷南缘西秋构造带深层发育有基底隆起。本文通过地震资料解释确认了西秋构造带深层古隆起的结构, 分析了古隆起的形成和演化过程。西秋构造带南侧边缘存在一条区域性基底断裂, 断裂北侧新生界下伏中生界、古生界明显减薄或地层缺失, 总体上表现为断背斜形态的古隆起构造。结合区域构造演化分析认为, 泥盆纪—石炭纪(D—C)塔里木克拉通边缘隆升、二叠纪—三叠纪(P—T)受南天山负荷影响产生的克拉通边缘压陷的构造演化过程中, 西秋构造带处于"跷跷板"式地壳升降运动的"支点"部位, 发育古隆起和基底卷入高角度断层, 晚期南天山隆升向南斜向推挤的挤压剪切应力场使古隆起边界断层复活, 基底断裂活动并在新生界之下形成冲断隆起。

Paleo-uplift formation and evolution in the Xiqiu structural belt of the Kuqa depression,Tarim Basin

Gravity anomaly data show that the Xiqiu tectonic belt in the southern margin of the Kuqa depression has developed as a basement uplift tectonic belt. The seismic data confirms the formation structure of the Xiqiu tectonic belt, and analyzes the processes of the formation and evolution of the ancient uplift. There are a regional basement-involved faults in the south edge of the Xiqiu tectonic belt, with obvious thinning of Paleozoic and Mesozoic thickness. The Paleozoic and Mesozoic strata have missed in the north edge of the faults, the whole ancient uplift performanced for faulted anticline structure. Combined with the regional tectonic evolution analysis, the edge of the Tarim Cratonic Basin has uplifted in Devonian and Carboniferous, the tectonic evolution process has been affected by the south of the Tianshan loading to form cratonic edge sag in Permian-Triassic. The Xiqiu tectonicbelt underwent tilting of crustal elevation and subsidence movement, has developed ancient uplift and high angle of basement-involved faults. The late transpressional stress field south of the Tianshan uplift due to oblique extrusion resulted in fault reactivation in the south of ancient uplift boundary, activities of the basement-involved faults resulted in the thrusting and uplifting under the Cenozoic strata.