塔里木盆地东南缘侏罗纪沉积相特征与古环境再造

Jurassic Sedimentary Facies and Paleoenvironmental Reconstruction of Southeastern Tarim Basin,Northwestern China

在沉积相和地震相特征分析的基础上,重建了塔里木盆地东南缘侏罗纪沉积古环境.结果表明:早侏罗世早期,塔里木盆地东南缘沉积以巨厚的冲积扇、辫状河三角洲为特征;早侏罗世晚期-中侏罗世早期,发育辫状河-辫状河三角洲、滨-浅湖沉积环境;中侏罗世中期,以湖相为主局部夹河流相;中侏罗世晚期,湖泊开始进入萎缩消亡阶段.阿尔金地区是盆地内主要的沉积沉降中心,塔里木盆地东南缘、柴达木盆地西部和吐拉地区相互连通,是古昆仑山前同一陆相盆地的不同组成部分,目前侏罗系展布格局是后期阿尔金山冲断隆升和阿尔金断裂走滑错断的结果.

The paleoenvironment of Jurassic in the southeastern Tarim basin was reconstructed based on the analysis of depositional and seismic facies. The results indicate that the depositional systems were consisted of alluvial-fan, braided-river delta at the early period of early Jurassic. From the later period of early Jurassic to the early period of middle Jurassic, the braided-river delta and littoral-shallow lake developed in this area. During the middle period of middle Jurassic, the depositional environment was mostly composed of lakes and rivers. At the late period of middle Jurassic, the lakes started to recess. The subsidence center of Jurassic was located in Altun. The southeastern Tarim, the western Qaidam basin and Tula basin were joined together at early-middle Jurassic, which are different compositional parts of the same continental basin at the foothill of Kunlun. The current distribution of Jurassic is resulted from thrust-uplifting of Altun mountain and slip-displacing of Altyn tagh fault.