新疆焉耆盆地早侏罗世八道湾期原始沉积边界探讨

Primary boundary of Early Jurassic Badaowanian sediments in the Yanqi basin Xinjiang

新疆焉耆盆地是一中、新生代盆地,通过对盆地下侏罗统八道湾组野外调研及地层岩石化学特征分析,笔者认为其物源区位于盆地北部,碎屑由北向南搬运,在北部为粗碎屑堆积,南部为细碎屑堆积;盆地北部为辫状河相沉积,南部为滨浅湖相沉积;最新完成的磷灰石裂变径迹数据显示西、南、北缘山体隆升较晚;在盆地周缘山体上,现今仍残留有侏罗纪地层;这都显示盆地原始沉积边界比现今盆地要广。通过以上分析及与库车盆地对比发现,两者于八道湾期是相连通的,为塔里木大型盆地的一部分。

The Yanqi basin of Xinjiang is a Meso-Cenozoic basin. According to the field survey and strata/rock geochemical analysis of the Lower Jurassic Badaowan Formation in the basin, the authors think that： the source area lies in the north of the basin and fragments were transported from north to south, with coarse fragments deposited in the north and fine fragments in the south; braided stream facies sediments occur in the north of the Yanqi basin, while lakeshore and shallow lake facies sediments in the south; and the new apatite fission track data show that the mountains on the western, southern, and northern margins of the Yanqi basin were uplifted late; and Jurassic strata stiU remain in mountains around the Yanqi basin at present. All these show that the primary sedimentary boundary of the basin is wider than that of the present basin. Based on the above analysis and its comparison with the Kuqa basin, the authors find that the Yanqi basin was connected with the Kuqa basin and that the two basins were a part of the Tarim basin in the Badaowanian period.