库车新生代构造性质和变形时间

NATURE AND TIMING OF THE KUQA CENOZOIC STRUCTURES

库车构造位于南天山古生代碰撞造山带之南，为塔里木盆地最北的一个构造带。它自北而南可分为边缘逆冲（ 隐伏构造楔） 、斯的克背斜带、北部线性背斜带、拜城盆地、南部背斜带。每个背斜带又包含有若干逆冲断层相关褶皱，它们是断层转折褶皱、断层传播褶皱、滑脱褶皱、断层传播 滑脱混生褶皱、双重逆冲构造、突发构造、三角带构造。底部逆冲断层向南变浅，堆叠逆冲岩席向南变薄，总体上形成一个向南的逆冲构造楔。逆冲断层在斯的克背斜带侵位最早（２５ Ｍａ） ，在北部线性背斜带为１６９ Ｍａ，拜城盆地中的大宛其背斜为３６ Ｍａ，南部背斜带为５３ Ｍａ（ 北部） 和１８ Ｍａ（ 南部） ，变形作用向南变新。库车构造是印 藏板块碰撞的内陆构造响应。

The Cenozoic Kuqa structures are located to the south of the southern Tianshan Paleozoic collision belt as the northernmost piece of Tarim Basin. They fall into (a) the marginal structural wedge,(b) the Shidike anticline zone,(c) the northern linear anticline zone,(d) the Baicheng Basin, and (e) the southern anticline zone from north to south.Each zone includes several thrusting related folds which are identified as fault bend folds,fault propagation folds, detachment folds,fault propagation detachment hybrid folds,duplex, pop ups and triangle zones.The sole thrusts are getting shallower southward from pre Jurassic to Neogene sliding strata and the stacked thrust sheets are thinning southward as well,therefore the total section shape of the Kuqa structures exhibits as a southward thrust wedge belt.The initial thrusting in the Shidike anticline zone is dated to 25Ma by the growth triangle,the northern linear anticline zone to 16 9Ma, the anticline in Baicheng Basin to 3 6Ma, the southern anticline zone to 5 3Ma(in north flank) and 1 8Ma(in south flank).So the thrusting emplaced since the beginning of Miocene till Quaternary and was younging southward.This crustal shortening is a response to the Indian Tibetan collision as the rejuvenation foreland basin deformation belt which is superimposed on the Permian foreland basin.