Longyong coalfield is the most important coal-rich belt which is located in the Late Paleozoic coal-accumulating basin in southwestern Fujian, South China. Tongzi Formation is the main coal-bearing rock series. On the basis of collecting geological data such as core, outcrop and well logging, the author analyzed Tongzi Formation in Longyong coalfield by using basic theory and research ideas of sequence stratigraphy, determined sequence boundaries, clarified its sequence stratigraphic framework and revealed the coal accumulation law of the coalfield. The results show that the Tongzi Formation has two key interfaces：The initial flooding surface and the maximum transgression surface. The initial flooding surface is located at the bottom of the No. Ⅱ key bed of the second segment of the Tongziyan Formation, and it is the interface of low-level system tract and transgressive system tract, and the interface of three-order sequence（sequence Ⅰ and sequence Ⅱ）. The maximum flooding surface is located in the top of mudstones of the second segment of the Tongziyan Formation, which is the interface between the transgressive system tract and the high water system tract in the third-order sequence Ⅱ. Type-Ⅰ sequence contains seven fourth-order sequences（parasequence S1～S6）, and Type-Ⅱ sequence contains six fourth-order sequences（parasequence S7～S12）. Type-Ⅰ sequence corresponds to the Wenbishan Formation and the first segment of the Tongziyan Formation, and Type-Ⅱ sequence corresponds to the second and third segment of the Tongziyan Formation. Coal accumulation mainly occurs in the high-level system tract. The most important coal accumulation of the Tongziyan Formation is developed in barrier island-lagoon sedimentary environments. The coal seams are mainly developed in the S3, S4, S9, S10 and S12 parasequences.
Xu Fumei Jiang Lin Bao Daoliang Liu Mingsong Qiu Zhanlin. Sequence stratigraphic framework and coal-accumulating patterns of the Tongziyan Formation in the Longyong coalfield[J]. Chinese Journal of Geology, 2019, 54(4): 1155-1166.