柴达木盆地侏罗系地层沉积大迁移及成因分析

GREAT TRANSPOSITION AND ORIGIN OF JURASSIC SEDIMENTARY IN QAIDAM BASIN

柴达木盆地早、中、晚侏罗世地层分布的变化较大 ,其沉积中心经历了自西北向北、再向东北的两次大迁移过程。在早侏罗世 ,盆地西北部边缘发育温暖潮湿气候下的断陷河湖沼泽沉积 ,中侏罗世以盆地北部边缘的广盆式断陷河湖沼泽沉积为特征 ,晚侏罗世以盆地东侧的山间凹陷干旱河湖沉积为主。对柴达木微板块西侧的中生代火山岩及与之相邻的塔里木板块、羌塘板块的地磁古纬度的对比分析表明 ,该盆地侏罗系板块之间不同性质的相互作用是控制其沉积 。

The stratigraphic distributions of Early Jurassic,Middle Jurassic and Late Jurassic in Qaidam Basin are greatly different.The deposit center had two times of great transpositions.The first transposition was from northwest to north,and the second one was from north to east.In the Early Jurassic,the paleoclimate was warm and damp,while the marshes,ravels and lakes in fault basin were distributed in the northwest.In the Middle Jurassic,the paleoclimate was warm and damp,while marshes,ravels and lakes in broad basin were distributed in the northern edge of the basin.In the Late Jurassic,the paleoclimate was dry,and mountain aprons were distributed in the east.The analyses on ages of granites in the northwestern basin and on the ancient latitudes of Qaidam plate,Tarim plate and Qiangtang plate based on paleomagnetic stratigraphy show that the origin of greatly sedimentary transpositions in Jurassic relied on the different interaction plates.