准噶尔盆地东北缘早石炭世南明水组沉积环境及构造背景分析

准噶尔盆地东北缘发育的下石炭统南明水组沉积岩是对晚古生代北疆地区洋壳俯冲消减作用的沉积响应。本次研究在南明水组地层中发现丰富的遗迹化石:Scalarituba, Planolites,Cosmorhaphe,Spirophycus和Helminthoida。岩性组合特征和遗迹化石所代表的遗迹相,反映了南明水组的主要沉积相类型为扇三角洲前缘、浅海、深海-半深海,从下往上为一个由浅变深再变浅的不对称的完整层序。南明水组的岩性、层序演化以及砂、泥岩地球化学特征表明,该套地层发育的构造背景为弧后盆地。早石炭世准噶尔盆地东部存在的洋壳俯冲消减作用是研究区弧后盆地发育的动力机制。

The depositional environment and tectonic setting of the Early Carboniferous Nanmingshui Group,in northeast margin of the Junggar Basin

The sedimentary rocks of the Lower Carboniferous Nanmingshui Group in the northeast margin of the Junggar Basin are depositional process response to the oceanic crust subduction in the Late Paleozoic,north Xinjiang area.Abundant ichnology fossils were found in the Nanmingshui Group,these ichnology fossils were mainly Scalarituba,Planolites,Cosmorhaphe,Spirophycus and Helminthoida.The rock and stratum assemblages and trace fossil facies reflect the sedimentary facies are fan delta front,shallow marine,hemipelagic to deep deposit,and formed a dissymmetry,complete sequence from the bottom to the top.The characteristic of lithology,sequence evolution and geochemistry values of sandstone and mudstone indicate that the Nanmingshui group deposited in a back arc basin.The Early Carboniferous oceanic crust subduction in the east Junggar Basin was the dynamic mechanism for the back arc basin formation in the margin of northeast Junggar Basin.