塔里木西南坳陷构造的几点新认识

NEW UNDERSTANDINGS OF DEPRESSION STRUCTURES IN SOUTHWESTERN TARIM BASIN

塔里木盆地西部巴楚以南,喀喇昆仑山、西南天山和麻扎塔格所夹持的地域,油气勘探已有半个多世纪的历史,已找到柯克亚、巴什托普、和田河等油气田.经过近年的研究,对该区的地质构造提出几点新认识.包括:古亚洲洋和特提斯洋是影响该区沉积和构造的主要因素;塔里木盆地西南坳陷两侧不对称;深浅层次构造差异较大;区内断裂和背斜多形成于喜玛拉雅构造运动.此外,根据大量野外实地考察和地震资料,对克里阳和乌恰地区构造进行了较为详细的研究.对玉立群背斜存在与否提出怀疑的意见,并对帕米尔前缘的的逆冲推覆构造样式进行了详细解剖,提出帕米尔山前存在3个相互叠覆推覆体的见解.

Over 50-year oil-gas exploration has been carried out in the area between Karakorum mountains, southwestern Tianshan mountains and Mazartag, south of Bachu in the western Tarim basin. Oil-gas fields have been found in Kekeya, Bashtopu and Hotan river. New understandings on geological structures of the area have been obtained after authors?research in recent years. It is regarded that paleo-Asian ocean and Tethyan ocean are the main factors controlling sedimentation and structure of the area, that structures on both sides of the depression are asymmetric, that structures at different depths are totally different, and that faults and folds were mainly formed during Himalayan orogeny. Based on seismic data and detailed field investigation in Keliyang and Wuqia, the author doubts the existence of Yuliqun anticline. A detailed analysis has been also made of thrust-nappe structures in the frontal Pamir. Suggestions are put forward of the existence of three overlapping nappe structures in the piedmont of Pamir.