塔中低凸起的形成和演化

Generation and evolution of Tazhong low uplift

根据对塔中地区及整个塔里木盆地构造 沉积特征 (构造应力场、构造格局、沉积环境及物源、火山活动、逆冲断层、地震反射特征 )的分析 ,认为塔中低凸起是塔里木板块南部与南昆仑板块在早奥陶世末相撞的产物 ,板块碰撞使塔里木板块北部的被动大陆边缘盆地与南部的弧后前陆盆地共存 ,唐古孜巴斯凹陷应属于弧后前陆盆地 ,塔中低凸起为前陆隆起 ,塔中Ⅰ号断裂为塔中前陆隆起冲断裂 ,其南部断裂为调节断裂或补偿断裂 ,此期形成的逆冲带成为后期阿尔金走滑断层活动的基础。论述了塔中前陆隆起的构造 沉积演化特点。塔中Ⅰ号断裂形成时间早 ,断距大 ,北部直接与生油凹陷相连 ,既是重要的油源断层 ,也是能改造储集层物性的重要断层 ,沿Ⅰ号断裂的潜山勘探应是今后塔中地区的重点勘探区域 ,东部的构造变形强度大于西部 ,勘探前景应好于西部。早、中奥陶世强烈的火山活动使塘古孜巴斯凹陷可能缺乏烃源岩 ,补偿断层主要在志留纪—泥盆纪形成 ,石炭纪以后基本上为稳定的整体升降 ,因此对该凹陷的勘探应格外慎重。图 4参

Based on analysis on structural sedimentary characters (including structural stress field, structural framework, sedimentary environments and sources, vocanic activities, thrusts and seismic reflection characters) of Tazhong region and the whole Tarim basin, it is considered that the Tazhong low uplift was generated by collision of southern Tarim Plate with southern Kunlun Plate at the end of early Ordovician which caused co existence of the passive margin basin in the northern part of Tarim Plate with the back arc foreland basin in the sorthern part. Tangguzibasi depression is a back arc foreland basin, and Tazhong low uplift is a foreland uplift, Tazhong No.1 fault is a thrust of Tazhong foreland uplift, faults to the south are accommodation faults or compensation faults. The thrust belts formed during this stage are pre existed fault belts for late Aerjing strike slip fault system. The authors of this paper also discussed structural sedimentary evolution characters of Tazhong foreland uplift. Tazhong No.1 fault was generated at early stage with large throw, and its northern part connected with the source depression. It is an important fault connecting with the source depression, and can also improve the quality of reservoir rocks. Buried hills along this fault should be important exploration areas. Its eastern part was more intensively deformed than the western part, therefore should be a better exploration area than western part. Intensive vocanic activities during early middle Ordovician might cause poor source rock development in the Tangguzibasi depression. Compensition faults were mainly developed during Silurian Devonian. Generally, Tangguzibasi depression was steadily uplifted after Carboniferous, therefore the special attention should be paid to in the exploration of this depression.