Study On The Late Paleozoic Sequence Stratigraphy Of Shanxi And Henan Areas

Based on the field survey measured sections and previous studies, using outcrop sequence stratigraphy of the research methods, we analysis the Late Paleozoic sequence stratigraphy of Shanxi and Henan areas. Main knowledge obtained as follows:(1) According to the lithology, sedimentary structure and fossil assemblages, the late Carboniferous and the early Permin stratigraphy can be divided into three depositional systems including carbonate platform system, clastic barrier lagoon system and delta system, and from which 8 sedimentary facies have been recognized. These facies are open platform, restricted platform, tidal flat, lagoon, barrier island, former delta, delta front and delta plain.(2) The sequence boundaries of the Shanxi and Henan areas are regional structural sendimentary facies transformation interfaces and regional unconformity. The parasequences in this area are shallowing upward parasequences, divided into three types: bottom type, debris barrier-platform type, clastic shore type.(3) By the detailed analysis of 46 sections in Shanxi and Henan areas, sequence stratigraphy can be divided into 11 third order sequences. The Carboniferous develop 4 third order sequences :Csq1~ Csq4 .And the Early Permian develop 7 third order sequences :Psq1~ Psq7. The sequence has"transgressive systems tract - highstand systems tract"dual structure characteristics.(4) By the trace and correlation of the 46 cross sections, the distributional framework and the regional changes of the third order sequences have been revealed. Late Carboniferous sequences are thick and full development in middle part of Shanxi, but to the south and north , the sequences number is gradually incomplete ,and the sedimentary thickness is become thinner. Late Carboniferous sequences develop completely in Henan area, but to north ,the upper sequence Psq6, Psq7 didn't develop gradually. As the changes of the sea level and palaeogeography, sedimentary characteristics of each sequence are also different in areas.(5) By the analysis of coal accumulating pattern, it is found that coal bed formed in different sedimentary environments: carbonate platform-the lagoon swamp, tidal flat peat bog environment, delta peat swamp environment. the coal beds are developed in both of the transgressive systems tract and the highstand systems tract, but the important coal beds are mainly concentrated in the highstand systems tract, that is because of the quick transgression and slow regression. The transgressive systems tract mainly forms coal line which is not stable in areas.