The coal bed in the lowstand system tract plays a increasingly significant role in the study of sequence division and the model of coal formation has become key issues. In this study, the theory that coal formation environment, whether it is a littoral environment or terrestrial environment, is generally the area of shoaly depression of the corrading stream or stream terrace has been proposed through analysis of coal formation sedimentary environment of marine lowstand system tract and nonmarine faulted basin lowstand system tract coalseam, space characteristics of lithology. Coal formation of marine lowstand system tract in coastal area mainly occurred in Neopaleozoic, its coal bed lesser and its progradation is marine deposit (limestone or claystone). While, in the nonmarine low stand system, coal formation are mainly found in Meso-cenozoic and the sedimentary particles of coal roof is coarser, this pattern is common in braided river, alluvial fan or fan delta. The coal seam in the lowstand system tract with complex structure, great difference in thickness and the quality of coal seam is poor. Based on the swing of Lake Basin water and the change of structural, there are high sulphur and ash in coastal area, high ash and more branch in the continental rift basin.
Keywords
Lowstand System Tract, Coal Formation Environment, Coal-Accumulation Model.
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