塔里木盆地基底卷入扭压构造与巴楚隆起的形成

在板块斜向碰撞中,与走滑断层相伴生的隆升是弯曲挤压的必然结果。印度板块与欧亚板块的斜向碰撞使得塔里木盆地边界和内部发育的基底卷入构造大多表现出逆冲与走滑断裂的双重特征。本文通过地震、钻井和构造几何学、地面资料约束研究表明,巴楚隆起两侧的阿恰-吐木休克和色力布亚-玛扎塔格断裂是由基底卷入构造和扭压构造复合而成的基底卷入扭压构造。这种构造样式的组合包括3个部分,即两端的基底走滑断裂和中段的基底卷入逆冲断裂。巴楚隆起的形成主要与阿恰-吐木休克断裂的基底卷入扭压构造活动有关。巴楚隆起的形成过程具有“跷跷板”特点,可分两个阶段:巴楚隆起前石炭纪沿南缘的玛扎塔格断裂抬升,地层最大剥蚀厚度至少530m;前古近纪,主要剥蚀区沿吐木休克断裂以南展布,推测最大剥蚀厚度超过1100m。巴楚隆起南段的主变形期是在前石炭纪完成的,地层缩短量约占55%;北段推迟到前古近纪,缩短量占55%;而中段的地层缩短量一直在逐步增强,前上新世达到最大,占52%。

Basement-Involved Transpressional Structure and the Formation of the Bachu Uplift,Tarim Basin,Northwestern China

The uplift concomitance with strike-slip faults is consequent on restraining bend in plate oblique collision. The oblique collision of the India and Eurasian plate cause the basement-involved structure of the Tarim Basin boundary and inside to put mostly up the double features as thrust and strike-slip fault. According to seismic, well data, remote sensing geology and structural geometry, this paper indicated the the basement-involved transpressional structure is a composite of basement-involved structure and basement-transpressional structure such as the Aqia-Tumuxiule faults and Selibuya-Mazatagh faults located on the both sides of the Bachu uplift. The combination of these structural styles consists of three sections: basement strike-slip faults on the both ends and basement-involved thrust in the middle part. The formation of the Bachu uplift mainly related to the action of basement-involved transpressional structure of the Aqia-Tumuxiule faults. The evolution of the Bachu uplift presents the characteristics of "Seesaw" and can divide into two periods: the southern Bachu uplift raised along the Mazatagh fault before the Carboniferous, the maximum erosional thickness at least 530 m; and before the Paleogene the main erosion area exhibited to the south of the Tumuxiuke fault, the maximum erosional thickness more than 1100 m. The main deformation of the southern Bachu uplift completed before the Carboniferous and the strata reduction is about 55%. The northern part had postponed to pre-Paleogene and the strata reduction is also about 55%. However, the strata reduction in the middle part of the Bachu uplift is different from the northern and southern parts and escalated at all times to reach the maximum before pre-Pliocene, and accounts for 52%.