Sequence Stratigraphy of the Sinian—Middle Devonian System in the Tarim Basin

Key words: 
• Tarim Basin /
• the Sinian&mdash /
• Middle Devonian /
• tectonism /
• sequence /
• geotectonic cycle /
• eustasy

Abstract: The Sinian—Middle Devonian System in the Tarim Basin can be divided into two I order sequences (megasequences), six II order sequences (supersequences) and seventeen III order sequences (sequences). The geotectonic evolution is characterized by the splitting and closing cycle of the Paleo-Xinjiang cratonic plate from the Sinian era to Middle Devonian period. The evolution of Tarim Basin underwent the craton marginal rift basin stage (Z-O) and the retro arc foreland basin stage (S-D2). The Megasequence I was composed of sediments of the craton marginal rift basin stage, of which the SupersequenceⅠA was the filling product of the continental rift basin filling during the Sinian era, the SupersequenceⅠB and the SupersequenceⅠC were the fills of the passive continental marginal depressional basin from the Cambrian era to the early Ordovician period, and the SupersequenceⅠD was the fills of the retro arc tensional basin in the middle-late Ordovician period. The MegasequenceⅡ standed for the sedimentation of the retro arc foreland basin stage, of which the SupersequenceⅡA in the East Tarim was the fills of retro arc foreland basin in the Silurian era and the SupersequenceⅡB was the filling product of the peripheral foreland basin in the early and middle Devonian period. It was proved by the study of the sequence stratigraphy of the Sinian～Middle Devonian system in the Tarim Basin that the tectonism controlled the formation of most of the 3-orders sequences. The eustasy finally played an important role in the formation of most of the sequences during the stable passive continental marginal depressional basin and intra-craton depressional basin evolution stage.