Study On Sequence Stratigraphic Framework Of The Permian And Triassic In The Dian-Qian-Gui Area

Guided by the theory of corn sequence stratigraphy, the Dian-Qian-Gui Area is selected to divide and correlate third-order sequences of the Permian and Triassic, and to draw the panel diagrams showing the sequence stratigraphic framework and the outline maps showing the palaeogeography of every third-order sequence, which are the fundament to draw the graphs showing the distribution of the genetic, reservoir and seal layer. Having effectively probed the filling succession characteristic of the Permian and Triassic of the study area, the evolution process of the palaeogeography, and the distribution nature of the genetic, reservoir and seal layer, and having further enhanced the forecast of exploration targets, this research method can be a new way to study carbonate strata areas of similar lower exploration. In accordance with the sedimentary characteristic of the carbonate strata area, meter-scale cyclic sequences, which are component units of third-order sequence, are applied as elementary study units to field survey and record, and indoor research. As a new method, this means reveal interior feature of sequence stratigraphy, and assure the accuracy and reliability of the division and correlation of sequence stratigraphy. In term of their geological meanings, sequence boundaries, which are division basis of third-order sequence, can be group into four types, which are tectonic unconformity, sedimentary unconformity, drowned unconformity, and their relative surfaces. The Permian can be divided into three series named as the Chuanshanian, Yangxinian, and Lepingian Series respectively. The top part of the Carboniferous and the Chuanshanian Series of the Permian form third-order sequence SQ19. The Yangxinian Series includes four third-order sequences from SQ20 to SQ23, and the Lepingian Series includes SQ24 and SQ25. The development of coal-bearing strata on the attached platform as well as the formation of sponge reefs in the margin of attached platform and on the isolated platforms make clear sedimentary facies differentiation and lead to a particular palaeogeographical pattern that is characterized by "platform-basin-hill-trough". The Triassic can be divided into three series named as the Lower, Middle, and Upper Triassic respectively. The Lower and Middle Triassic both can be divided into three third-order sequences (from SQ26 to SQ28 and from SQ29 to SQ31). The Upper Triassic includes four third-order sequences from SQ32 to SQ35. From the attached platform to the turbidity basin, the sedimentary facies differentiation is very clear.