塔里木盆地深部构造与震旦纪裂谷

塔里木盆地是一个发育在塔里木反块中部的大型克拉通盆地，它位于一近东西向展布的地幔隆起之上，其地壳厚度为４１～５０ｋｍ。盆地基底结构复杂，由太古界—下元古界深变质岩系和中上元古界浅变质岩系经８００Ｍａ前的热构造事件拼合固结而成。基底四周被深大断裂切割，控制和影响着盆地的形成与演化。震旦纪，岩石圈伸展分裂，塔里木盆地南北缘均为被动大陆边缘，其裂谷作用具有北强南弱东强西弱的特点。因此，在盆地部形成夭折裂谷，盆地西南则表现为克拉通内坳陷

INFRA STRUCTURE AND SINIAN RIFT OF TARIM BASIN

Tarim basin is a giant Craton basin which occupies the central part of Tarim plate.There is an east west trending mantle dome beneath the basin.Its crustal thickness ranges between 41-50km There is a complicated structure of besement rocks beneath the basin.Three types of magnetic features are shown on the aeromtnetic anomaly map of Tarim bsain.The basement rocks consist of high grade metamorphic rocks of Archaean-Lower Proterozoic and lower grade metamorphic rocks of Middle Upper Proterozoic and are mosaicked/consoidated by tectonic events 800 Ma ago .The peripheral basement rocks are bordered by some deep seated faults .They play an important role in the control for the formation and sedimentary tectonic evolution of the basin. The extension and rifting processes of the lithosphere occurred during Sinian,thus both of the northern and sorthern margins of Tarim basin are passive continental margins,and consequently the fault depression and sedimentation are developed within the basin.Riftogenesis exhibits stronger in the north and east parts of the basin and weaker in the south and west parts. So a failed rift (Manjiaer aulacogen )is formed at the north flank of the basin and a intra Craton depression (Southwest depression )in the south part of the basin. Sinian strata are the first and the lowest cover on the basement rocks of Tarim basin.Because rifting process was weak during Early Sinian,the distributive provinces of Lower Sinian strata are limited within the margins and northeast part of the basin.As strengehening riftogenesis,Upper Sinian strata spread all over the basin.There was an approximate east weat trending tectonic framework regionally with alternating uplifts and depressions during Later Sinian,that is ,northern uplift,central uplift,Manjiaer aulacogen and southwest depression.Carbonate rocks,petroclastic rocks,vlocaniclastic rocks and volcanic rocks of shelf bathysl facies are deposited in Manjiaer aulacogen and also carbonate rocks of shelf facies are deposited in southwest depoession.