Intergrative Stratigraphy Of The Upper Permian Wujiaping Stage In Wenshan-Guangnan Region Of Southeastern Yunnan

This paper selects Tianshengqiao-Zhewushe mining area and Shazitang-Banmao mining area as research area. The two mining areas respectively belong to Wenshan county and Guagnnan county, both in Wenshan Zhuang-miao Autonomous Prefecture, Yunnan province. The research age is Late Permian early Wujiaping age, which is corresponding the depositing age of lower Longtan formation (Wujiaping). This paper studies the comprehensive stratigraphy of main mineralization stages of bauxite mine in research area, and builds strata framework through comprehensive study and sequence comparion of lithostratigraphy, biostratigraphy, and sequence stratigraphy of the two mining areas. On this basis, the space-time distribution law of each sedimentary system is discussed. This paper mainly obtains following results:(1) Lithostratigraphy research:According to the study on lithostratigraphic division, distribution and lithologic assemblages of Permian and its adjacent strata, in the two mining area. From bottom to up, the stratas of Tianshengqiao-Zhewushe mining area are divided into Huanglong formation(C2h), Emeishan basalt(P2-3β), Longtan formation(P3l) and Feixianguan formation(T1f); And the stratas of Shazitang-Banmao mining area are divided into the Huanglong formation(C2h), Maping formation(C2m+P1m), Yangxin formation(P2y), Wujiaping formation(P3w) and Changxing formation(P3ch).(2) Biostratigraphy research:Fusulinid fossils in the area are divided into16genera and38species,16genera including Fusulinella, Profusulinella, Fusulina, Misellina, Maklaya, Reichelina, Paleofusulina and so on. And four fossil zones are divided, that is, Fusulina-Fusulinella assemblage zone, Misellina range zone, Reichelina-Sphearulina assemblage zone and Palaeofusulina zone.(3) Sequence stratigraphy research:Two types of sequence boundaries are identified:regional unconformity interface-type Ⅰ sequence boundaries, widely developed carbonaceous mudstone and coal seam-type Ⅱ sequence boundary; both interfaces are key to divide the sequence types and system tract. According to stacking style of sequence boundaries and parasequence, and superposition pattern of parasequence group, the sequences of76sections are divided, and two third-order sequences mainly be developed in study area. Based on sequence stratigraphic division and correlation, the sequence stratigraphic framework of Late Permian early Wujiaping age has been builded in Tianshengqiao-Zhewushe mining area and Shazitang-Banmao mining area. According to analysis of sequence stratigraphic framework in the two mining area, the target interval deposits in Tianshengqiao-Zhewushe mining area are greatly influenced by the morphology of sedimentary basement; the transgression direction in Shazitang-Banmao mining area was from north-east direction.