The depositional environment and tectonic setting of the Early Carboniferous Nanmingshui Group, in northeast margin of the Junggar Basin
Tao Huifei, Wang Qingchen, Sun Su, Yang Xiaofa, Jiang Lin
1. State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;
2. Key Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Lanzhou 730000;
3. Graduate University of Chinese Academy of Sciences,Beijing 100049
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.