Correlation of the Early Permian sedimentary evolution between north side and south side of East Tianshan Mountains

Based on the previous study and new geological data, the authors made a comparative study of sedimentary sequences, lithofacies and paleocurrents of the Early Permian period on the south side and north side of East Tianshan Mountains and discussed the possible evolution of the basins. The Early Permian Shirenzigou Formation and Tashenkula Formation, developed on the north side of East Tianshan Mountains, were mainly composed of pillow basalt, rhyolite, carbonate flysch deposits, siltstone with marine fossils, etc. and suggested a marine rift basin, The Taoxigou Group and Yierxitu Formation on the south side of East Tianshan Mountains contain andesite, rhyolite and pyroclastic rocks interbedded with non-marine clastic rocks, implies a continental(non-marine) rift basin. Provenance analysis shows that paleocurrents in SE direction existed in the north of East Tianshan Mountains. On the contrary, paleocurrents in the south showed a northwest direction and provenances were from the underlying Pre-Permian lithological associations. It is suggested that the Bogeda area was a depositional center in East Tianshan Mountains in the Early Permian period and marine rifts were located in the north of East Tianshan Mountains and non-marine rifts were dominantly in the south. However, they were integrated into a large non-marine basin in late Early Permian. Researches indicate that the difference in sedimentary environment between the north side and south side of East Tianshan Mountains was mainly caused by different evolution processes in the east and west of Bogeda rift in the Carboniferous period.