| The study area is bounded by Sunan to the west of Gansu, Tongxin of Ningxia tothe east, Zhangye and Wuwei area to the north, Tianzhu and Jingyuan area to thesouth. on the basis of theories of Sedimentary geology, petrology, Lithofaciespaleogeography and the investigation of filed sections and analysis of sedimentaryfacies, coupled with previous study, the following fruitfull results have been achieved:The research of main lithology of lower Carboniferous in Hexi Corridor ofGansu prov.ince have been conducted by outcrop observation and thin sliceindentification, and limestone, dolomite, sandstone, mud(shale), cherts, gypsum andcoal are recognized as seven main types, among which limestone, sandstone, mud arethe majority and dolomite, gypsum and coal usually locate in limited area.According to the lithology, sedimentary structure and fossil assemblages， adetailed sedimentary facies division for lower Carboniferous in research area havebeen made and4sedimentary systems and8sedimentary facies and severalSedimentary micro facies have been identified. Four sedimentary systems arecarbonate platform, shallow water system, the barrier-tidal flat-lagoon system anddelta system separately;8sedimentary facies include open platform facies, restrictedplatform, shallow marine, tidal flat, lagoon, barrier Island phase, Gulf and delta faciesUnder the analysis of facies sequence configuration,3sedimentary three-level-cycles have been divided after a detailed division for sedimentary cycle of4sectionsin research area. The number of cycle in different section is not the same because ofthe difference of strata integrity.According to horizontal contrast of29sections, an Early Carboniferouslithofacies paleogeography map of Hexi Corridor in unit of stage have beenelaborated by mapping method of univariate analysis and multifactor comprehensive.A detailed conclusion about distribution characteristic of major sedimentary faciesand palaeogeographic evolution are made. |
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