南天山库车褶皱冲断带的伸展构造

为利于库车地区天然气的勘探与开发,对该区构造提出了一些不同的认识。通常认为,自渐新世晚期至今,南天山库车地区一直处于南北向挤压构造环境。但实地考察发现,新生界地层不仅被推覆构造卷入,而且亦有受到南北向拉张构造的改造,发育有5种伸展构造:挤缩地质体后部的块断伸展构造(块断构造)、挤缩地质体的反向伸展构造(反向正断层)、挤缩地质体的横向伸展构造(横向正断层)、挤缩地质体的反转伸展构造(负反转构造)、挤缩地质体隆起部的裂陷伸展构造(正地堑)。收缩与拉伸构造的关系表现为,在同一地段,早时挤缩褶冲,后时伸展块断,先后复合;在同一时段,前缘挤缩冲断,后缘伸展正断,前后并列。南天山构造地貌景观表明,通常被否定的我国西北地区含油气盆地的伸展构造是实在的,且与推覆构造相随相伴,这对于该区推覆构造控气与伸展构造调气的分析评价具有实际意义

EXTENSIONAL TECTONICS IN KUQA FOLD AND THRUST BELT IN SOUTH TIANSHAN MOUNTAIN

Some different comments of tectonics in Kuqa area are presented, which will profit exploration and exploitation of natural gas. It is usual viewpoint that the area is always in compressed tectonic background since late stage of Oligocene. It is adverted that Cenozoic stratum is not only involved by nappe tectonics, but also remodeled by NS extensional tectonics. There are five class of extensional tectonics: Fault-block Tectonics, which develops in the after part of compressed geologic body; Antithetic extensional tectonic (antithetic normal fault); Lateral extensional tectonic (lateral normal fault); Inverse extensional tectonic (negative inversion-tectonics); Taphrogenic extensional tectonic (normal graben), which develops in the uplift of compressed geologic body. The geologic body happens fold and thrust early because of extrusion and fault-block later because of stretch in the same area, and thrust in the foreside because of extrusion and normal fault in the backside because of stretch on the same time. The extensional tectonics exists in the margin of basins in northwest China, which is usually negated, and develops together with nappe tectonic.