塔里木盆地早、中寒武世古地理与沉积演化

基于二维地震剖面精细解释，结合最新钻井地质资料分析，在构造控沉积的指导思想下，对塔里木盆地早、中寒武世岩相古地理及沉积演化进行研究。塔里木盆地早寒武世构造古地理整体呈现“中间高、南北低”的隆-坳格局，巴楚隆起-塔中隆起东部一带发育近东西向展布的同沉积古隆起，往北和往西南方向由隆起向坳陷逐渐过渡。早寒武世玉尔吐斯组沉积期塔里木盆地为以深水陆棚为主的缓坡沉积，由中央古隆起向南北两侧依次发育潮坪相、斜坡相和深水盆地相；早寒武世肖尔布拉克组沉积期塔里木盆地为具有一定台地性质的碳酸盐岩缓坡沉积，由中央古隆起向南北两侧依次发育内缓坡、中缓坡、外缓坡和盆地相，外缓坡在地震资料上可见典型前积反射特征，反映为远端变陡的缓坡。研究证实了塔里木盆地早寒武世中央古陆的存在，并初步厘定了早寒武世玉尔吐斯组和肖尔布拉克组沉积期古陆及相应的沉积相带展布。通过构造-沉积演化分析，首次明确了塔里木盆地早寒武世并没有形成真正意义上的碳酸盐台地，而是受整体上南北分异的隆-坳构造格局控制的缓坡沉积模式，至中寒武世中西部大台地才逐渐形成。

Early-Middle Cambrian paleogeography and depositional evolution of Tarim Basin

Conforming to the guideline that tectonism controls sedimentation,the study investigated the Early and Middle Cambrian paleogeography and depositional evolution of Tarim Basin based on fine interpretation of 2D seismic profile and analysis of the latest drilling geological data.In the Early Cambrian,the tectonic paleogeography in Tarim Basin was characterized by the "framework with one uplift located between a southern and a northern depressions":a nearly EW-trending synsedimentary palaeohigh occurring in Bachu and eastern Tazhong uplift areas,and transiting to depressions in both the north and southwest directions.During the sedimentary period of the Yurtusi Formation in the Early Cambrian,Tarim Basin was a ramp with the deepwater shelf being dominant,and the tidal flat,slope,deepwater basin facies were successively developed along both the south and north sides of the central palaeohigh.But during the sedimentary period of the Xiaorbulak Formation in the Early Cambrian,Tarim Basin was a carbonate ramp of certain platform characters;the inner,middle and outer ramp facies and basin facies were developed along both the south and north sides of the central palaeohigh;and the outer ramp facies shows typical reflectance signatures of progradation on seismic sections.This study confirmed the existence of the central paleo-continent of the Early Cambrian in Tarim Basin,and preliminarily revealed the distribution of the paleo-continent and the relevant sedimentary facies belts of the Early Cambrian Yurtusi Formation and Xiaorbulak Formation.Through tectonic and sedimentary evolution analysis,we were sure,for the first time,that the Early Cambrian Tarim Basin was a ramp controlled by a north-south differential tectonic pattern instead of a carbonate platform in the real sense of the term.The platform in the western-central Tarim Basin came into being until the Middle Cambrian.