塔里木盆地早中寒武世张裂构造及沉积响应

EXTENSIONAL TECTONIC CHARACTERISTICS AND ITS SEDIMENTARY RESPONSE OF EARLY-MIDDLE CAMBRIAN IN TARIM BASIN

塔里木盆地塔中、巴楚地区中下寒武统发育半地堑和正断裂,说明早中寒武世塔里木盆地为张裂构造环境;半地堑在平面上呈带状分布,纵向发育具有继承性;正断层的平面组合形态呈侧列式和雁列式,断层断距自西向东逐渐增大。张裂构造是离散大陆边缘形成时强烈拉张作用的产物,半地堑的形成与塔西南被动大陆边缘和塔东克拉通边缘拗陷的形成有关,受盆地东北缘三叉裂谷系发育的影响更为明显。断裂体系控制着盆地的沉积格局和充填演化,盆地整体呈现台地相—斜坡相—半深海盆地相的沉积格局,而半地堑的走向呈NW—SE向,与隐伏基底断裂走向一致,其沉积模式为灰岩—云岩—膏岩—盐岩—红层沉积。

The half grabens and normal faults develop in the Lower-Middle Cambrian of Tazhong(central TarimBasin)and Bachu area,Tarim Basin,which indicates that Tarim Basin may be of extensional tectonic setting duringthe Early-Middle Cambrian.The half grabens are distributed within a linear zone laterally and show verticalsuccession,while the normal faults are arranged in echelon patterns and the fault throw increases gradually fromwest to east.Such extensional tectonics may be the result of intense stretch in connection with the formation ofdiscrete continents.The formation of half grabens,associated with the formation of passive continental margin inthe southwest and cratonic marginal depression in the east,especially is notably influenced by the development oftrigeminal rift on the northeast margin of Tarim Basin.The fault system controls the sedimentary filling evolutionand framework which exhibits platform-slope-bathyal facies.The half grabens trend NW-SE,consistent with buriedbasement fault,and the lithology is limestone-dolomite-gypsum rock-saline rock-red layer sediments.