新疆西北部和什托洛盖盆地构造演化与后期走滑冲断改造

摘要

和什托洛盖盆地位于新疆西北部，是在西准噶尔晚古生代造山带逆冲推覆构造系统之上发育的一个中新生代沉积盆地。关于盆地演化和盆地性质的认识分歧较大。为了恢复盆地形成与演化历史，分析盆地性质，采用改造型盆地的研究思路，开展了地震剖面构造解析和区域地质综合研究。结果表明，三叠纪以来该区至少经历了3个成盆与改造期：印支期为挤压坳陷盆地，形成了和什托洛盖盆地的雏形；燕山期为伸展坳陷盆地，晚期遭受走滑冲断改造，盆地现今南北对冲的构造格局基本形成；喜山期主要表现为先存断裂复活，盆地隆升并遭受强烈改造，最终形成现今的构造地貌形态。尽管不同成盆期的区域应力场和盆地性质各具特点，但各成盆期后期改造阶段的区域应力场特征基本一致，主要受盆地北缘谢米斯台山山前断裂向南冲断和达尔布特断裂左行压扭走滑所形成的压扭应力场控制。因此，和什托洛盖盆地总体是一个由区域应力场性质在中新生代发生多次改变所形成的走滑冲断改造盆地。%Hoxtolgay basin,located in northwestern Xinjiang,is a Mesozoic-Cenozoic sedimentary basin developed on the thrust nappe system of the west Junggar orogenic belt formed in late Pale-ozoic.There exists an ongoing debate in understanding of the basin prototype and its evolutionary history in Mesozoic-Cenozoic period.To restore the history of formation and evolution,and de-termine the type of the basin,research ideas of reformed basin was applied to analysis of forma-tion and development of the basin,the comprehensive geological studies and seismic structural a-nalysis were carried out as well.Results show that the formation and evolution of Hoxtolgay Ba-sin in Mesozoic-Cenozoic age is mainly influenced by west Junggar orogeny,and can be subdivided into at least three basin formation and reformation periodssince Triassic,respectively Indosinian,Yanshanian and Himalayan period.The prototype of the basin in Indosinianis a compressional de-pression controlled by the east-westtrending Xiemisitaishan piedmont thrust fault,and developed an extensional depression with a large scale subsidence in Yanshan period.At late Yanshanian, the basin was strongly reformed by folding and thrusting,and the north-south ramp framework of the basin wasformed.The sedimentary area of the basin was greatly narrowed and restricted to the middle depression belt of the basin in late Yanshanian to Himalayan period,and mainly exhib-ited the characteristics of the reactivity and inheritance of the pre-existing faults.Although the tectonic stress fields and basin features are different in different stages of formation and develop-ment of the basin,their regional tectonic stress fields are generally the same or similar in the later stage of each basin development,mainly due to Xiemisitaishan Piedmont fault thrusting south-ward and Daerbute sinistral transpressional faulting.It is therefore concluded that Hoxtolgay ba-sin is generally a strike-slip and thrust reformed basin caused by the changes of the regional tec-tonic stress fields in the process of basin evolution.