塔里木盆地早白垩世沉积相特征与古地理

根据大量的钻井和露头资料，对塔里木盆地早白垩世沉积相特征和古地理进行了研究。塔里木盆地下白垩统主要发育冲积扇-扇三角洲、辫状河三角洲、氧化宽浅湖泊等3种沉积体系，包括陆相冲（洪）积扇、扇三角洲、辫状河三角洲、滨浅湖等沉积相，分布于下白垩统不同层位。塔里木盆地早白垩世主要包括塔东北和塔西南两大沉积区，总体为干旱氧化的内陆拗陷分割盆地。在塔东北沉积大区，早白垩世早期卡普沙良群沉积物受周缘4大物源区控制，为多物源的氧化宽浅湖盆环境，古地势呈“南高北低、东高西低”，盆地边缘以冲（洪）积扇、扇三角洲、辫状河三角洲相为主，盆地内部为滨浅湖亚相。早白垩世晚期巴什基奇克组沉积时期，塔里木盆地周缘进入一个新的构造活动期，古气候更加炎热干旱，氧化宽浅湖盆消失。在塔东北沉积大区，盆地受周缘4个主要物源区影响，以广泛分布的冲积扇-辫状河三角洲沉积体系占主体，盆地内部普遍为辫状河三角洲前缘-滨浅湖亚相沉积。在塔西南沉积大区，早白垩世克孜勒苏群沉积时期古地势呈“东高西低”，受北部喀什北山前和西南部古昆仑山2个物源区的控制，沉积物沿古昆仑山前呈狭长的条带状分布，沉积厚度自西向东减薄，主要是一套冲积扇-扇三角洲相和滨浅湖亚相沉积。

Sedimentary characteristics and palaeogeography of the Early Cretaceous in Tarim Basin

Based on the plentiful data of drilling wells and outcrops， the sedimentary characteristics and palaeogeography of the Early Cretaceous have been analyzed. Continental alluvial(or pluvial)fan facies， fan delta facies， braided fluvial delta facies and lacustrine facies were developed in the Lower Cretaceous. They were widely distributed throughout  the Lower Cretaceous. Sedimentary systems are dominated by three types: alluvial fan-fan delta， braided fluvial delta， and shallow lacustrine.In the Tarim Basin,  Early Cretaceous deposition occurred in two areas: northeastern and southwestern part. The basin was an  inland separated depressional basin with arid and oxygenative climate conditions. During the deposition of the Kapushaliang Group in the early Early Cretaceous， shallow lacustrine basin with multi-provenances develop in the northeastern area of the Tarim Basin. The sediments were controlled by four provenances surrounding the basin. The topography of the basin was higher in the south， and lower in the north, and higher in the east, lower in the  west. There were mainly alluvial fan， fan-delta， and braided fluvial delta in the basin margin， and lacustrine facies in the hinterland of the basin. During the deposition of the Bashijiqike Formation in the late Early Cretaceous， a new tectonic activity period occurred in the margins of the Tarim Basin. The palaeoclimate was more torrid and arid. The lacustrine basin disappeared. Controlled by the four provenances， the extensive coarse grain alluvial fan and braided fluvial delta systems were mainly developed in the northeastern  Tarim Basin. The topography of the southwestern  Tarim Basin was higher in the west and lower in the east during the deposition of the Kezilesu Group. Controlled by the two provenances in the north of Kashi Mountain and palaeo-Kunlun Mountain， the sediments were distributed in the front of palaeo-Kunlun Mountain in a long and narrow belt. Mainly alluvial fan—fan-delta—shore-shallow lacustrine facies were developed， with thickness decreasing from west to east.