Sequence Stratigraphic Analysis of Carboniferous in Wuwei Basin

A systematic study on sequence stratigraphy of 13 Carboniferous outcrop sections in Wuwei Basin had been conducted to identify two type Ⅰ sequence boundaries,four type Ⅱ sequence boundaries,five sequences and 11 systems tracts.TypeⅠsequence boundary had two genetic types.One genetic type was the tectonic unconformity interface influenced by the regional tectonic movements,the other genetic type was the erosion or sequence missing influenced by the local lift-down movements.The type Ⅱ sequence boundary was mainly the structure transition interface by the significant change in the sedimentary structure.The sequence Ⅰ,sequence Ⅱ,sequence Ⅲ,sequence Ⅳ,sequenceⅤ were basically matched with Qianheishan Formation,Chouniugou Formation,Jingyuan Formation,Yanghugou Formation and Taiyuan Formation.For the first time,the low stand systems composed by down-cutting stream phase complex had been discriminated in the bottom of Qianheishan Formation of the Early Carboniferous.We revealed the development characteristics of different systems tracts within the sequence and set up the sequence stratigraphic framework of Carboniferous in Wuwei Basin,analyzed the evolution of sequence and systems tracts and the change law of sedimentary environments.