摘要
我们已完成了穿越准噶尔盆地及其周边地区的I-I、II-II、III-III、IV-IV和额敏—哈密剖面5条综合地球物理剖面。通过综合研究,初步了解准噶尔盆地及邻近地区的地球动力学问题:准噶尔盆地基底由北部的乌伦古地体和南部的玛纳斯地体组成。两者的分界为西西北方向的滴水泉—三个泉缝合线。其西部与北东向Dalbutte缝合带相连,东部与北西向的Cranamary缝合带相连。准噶尔盆地北部的乌伦古地体基底为双层构造,上层为泥盆系和下石炭统组成的褶皱基底,大致表现为北厚(3~5 km)、南薄(1~2 km)。缝合线以南的玛纳斯地体为单层基底,即新元古代结晶基底。准噶尔盆地地壳厚度为44~52 km,北薄南厚。周边山区地壳厚度高于盆地地区。盆地及邻近地区地壳分为上、中、下层,并且中地壳一般较薄。盆地地区的地壳存在多条深断裂。南北方向发育了6条主要深断裂,分别为红车、德伦山、石溪、呼图壁、彩南和阜康。这些断层倾角较大,向上延伸至上地壳下部,向下切入地壳基底界面。壳内水平构造和构造面无明显垂向断层,似有“开放断层”特征。这些断层是上地幔物质挤入地壳的良好通道。此外,该地区还有两条主要的横向深断层。一是北西西走向的滴水泉—三个泉深断裂,它向南倾斜,具有逆断层性质,可能会破坏滴水泉—三个泉缝合带。另一条是近东西向的昌吉—玛纳斯深断裂,向南倾斜,主要发育在中下地壳,具有逆断层性质。这些深断裂对盆地构造发育具有一定的控制作用。准噶尔盆地西部的莫霍面基本连续地延伸到了天山的莫霍面,并且后者的莫霍面深度明显大于前者。但是,盆地东部的莫霍面与博格达山脉的莫霍面并不连续。前者以叠加关系延伸到后者之下,表明盆地东部的地壳向博格达山脉俯冲。这有助于解释天山东部构造活动相对减弱而博格达山脉�
Five comprehensive geophysical profiles,I-I,II-II,III-III,IV-IV and Emin Hami,have been completed across the Junggar Basin and surrounding areas.A preliminary understanding of the geodynamic problems in the greater Junggar Basin is achieved through comprehensive research.The basement of the Junggar Basin is composed of the Wulungu Terrane in the north and the Manas Terrane in the south.The boundary between the two is the Dishuiquan Sangequan suture in the NWW direction.It is connected to the NE-trending Dalbutte suture in the west and the NW-trending Cranamary suture zone in the east.The basement of the Wulungu Terrane in the northern Junggar Basin has a double-layered structure,where the upper layer is a folded basement composed of Devonian and Lower Carboniferous rocks,generally thick(35 km)in the north and thin(12 km)in the south.The Manasi Terrane south of the suture line has a single layer basement,namely the crystallization basement of the middle to upper Proterozoic.The crust in the Junggar Basin,4452 km thick,is thin in the north and thick in the south,while the crust in the surrounding mountainous area is thicker compared to the basin area.The crust in the basin area is divided into upper,middle(generally thinner)and lower layers and contains several deep faults.Six major deep faults are in the north-south direction:Hongche,Delunshan,Shixi,Hutubi,Cainan and Fukang.These faults have large dips,extending upward to the lower part of the upper crust and cutting down through the basement interface of the crust.The horizontal structure and structural plane of the crust have no obvious vertical fault or seem to have the feature of“open fault”.These faults are good channels for the upper mantle material squeezing into the Earth s crust.In addition,there are two main transverse deep faults,one is the Dishuiquan Sangequan deep fault with an NWW strike.It dips to the south and has the property of reverse fault,and it may break the Dishuiquan Sangequan suture.The other is the near EW Changji Manas deep fault dip
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2021年第6期235-255,共21页
Earth Science Frontiers
关键词
准噶尔盆地
壳幔结构
基底结构
基底性质
地球动力学过程
Junggar Basin
crustal and mantle structure
basement structure
basement property
geodynamic processes
