Stratigraphic sequence classification of Longhuichang-Tieshan area in Northeast Sichuan

The phase change of the 2nd member of Feixianguan formation in Longhuichang-Tieshan area led to great difficulty in stratigraphic classification and correlation of T1f1~T1f3.As there are different standards in stratigraphic sequence classification,the sedimentary facies distribution range can not be accurately described.By using the theory of stratigraphic sequence,taking the maximum flooding surface as the guidance,the stratified interface between Changxin formation and Feixianguan formation has been determined,and the depositional cycle has been taken for representation.From the correlation of lithology and electrical property,5depositional cycles have been classified from the bottom to the top of Feixianguan formation,the stratigraphic sequence framework has been established to carry out comparative analysis,and fine description of sedimentary facies belt has been conducted within the isochrono-stratigraphic units,which lays a solid foundation for good recognizing lateral and vertical distribution of favorable microfacies within the isochrono-stratigraphic units.