Delicata Sedimentary Model to Lianglitage Formation of Upper Ordovicianin the Northern Margin of Isolated Platform in the Center of Tarim Basin

Key words: 
• Ordovician

Abstract: By analysing abundant crop and core data, Lianglitage Formation of Upper Ordovician in the northern margin of isolated platform has been identified five microfaces which are bank, bafflereef, algae mat, subtidal low energy zone. According to the highlow order of depositional energy, it constructs high frequency sedimentary group(reefbank,reefbandmound,bankmound, grainstone bank,bankalgae mat,moundalgae mat, algae mat,low energy zonealgae mat) and analyses this eight depositional group evolution rule under the sequence framework.On this basis, synthesizing seismic data and research result of predecessors, it is divided into four aggradating rimmedshelf sedimentary models delicately:1)faultcontrolling narrow and sharp rimmed platform,taking Tazhong 261 area for example; 2)faultcontrolling wide and sharp rimmed platform,taking Tazhong 621 area for example; 3)depositing wide and sharp rimmed platform,taking Tazhong 82 area for example; 4)depositing wide and gentle rimmed platform,taking Tazhong 452 area for example. Faultcontrolling platform margin has high energy, which is beneficial for reefbeach complex growth.These established models provide a valuable reference for Lianglitage Formation's exploration.