川东金刚矿区须家河组层序-古地理及聚煤特征

利用钻孔岩心、野外露头、测井等资料，对四川盆地东部金刚矿区上三叠统须家河组层序-古地理及聚煤特征进行研究。根据地层颜色突变面、河流下切谷冲刷面以及沉积相转换面3种典型层序界面，将研究区须家河组划分为4个三级层序，其中层序III对应须家河组四段和五段，层序IV对应须家河组六段和七段，以三级层序为作图单元，恢复了各层序的古地理格局，主要的古地理单元为曲流河和河流三角洲，物源为东南侧的江南古陆；层序IV的聚煤作用明显优于层序III，湖侵体系域更有利于成煤；层序III的煤层多发育在下三角洲平原分流间湾沉积中，层序IV的煤层主要发育于曲流河的岸后沼泽。 

Sequence-paleogeography and coal -accumulation of Xujiahe Formation in Jingang mining area of eastern Sichuan basin

Sequence-paleogeography and coal-accumulating characteristics of the Late Triassic Xujiahe Formation in Jingang mining area of eastern Sichuan basin were studied based on the data from outcrops, borehole cores, and geophysical logging. According to the color discontinuity surface of strata, basal erosional surfaces of the incised valley filled with sandstone and the vertical facies reversal surface, four third-order sequences were subdivided in Xujiahe Formation, in which sequence III and sequence IV representing the coal-bearing members in the study area, were corresponding respectively to the intervals from member 4 to member 5 and from member 6 to member 7. Taking the third order sequences as the mapping unit, we have reconstructed the lithofacies-paleogeography pattern of sequence III and sequence IV. During deposition of sequence III and sequence IV, the main paleogeographical units were the meandering river and fluvial delta, with Jiangnan Oldland to the east as the major provenance. The mineable coal seams were mainly developed in the transgressive systems tract (TST), with relatively thick coals in sequence IV. The coal in sequence III was deposited in the interdistributary bay of the lower delta plain environment and the coal in sequence IV was formed in the back swamp of the meandering river environment.