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山西省石炭-二叠纪含煤岩系层序-古地理与聚煤特征

Characteristics sequence-palaeogeography and coal accumulation ofPermo-Carboniferous coal measures in Shanxi Province

  • 摘要: 为得到山西省石炭-二叠纪等时地层格架下的聚煤规律,利用煤层露头及钻孔资料分析了含煤岩系岩相组合特征,绘制地层厚度、石灰岩含量、砂泥比、煤层厚度等值线图。研究结果表明:在山西省石炭-二叠纪含煤岩系中划分出碳酸盐台地-障壁-潟湖、三角洲、河流、湖泊等4大沉积体系,可将本溪组、太原组和山西组划分为3个三级层序,恢复了各层序的岩相古地理,主要的古地理单元有河流、三角洲、障壁岛、潮坪-潟湖和碳酸盐台地等,海侵方向由层序Ⅰ的北东向转变为层序Ⅱ和Ⅲ的南东向,且层序Ⅰ煤层形成于潮坪-潟湖环境,层序Ⅱ和Ⅲ煤层形成于三角洲平原环境,同时聚煤中心从层序Ⅰ至层序Ⅲ期有从北向南迁移的规律,以层序Ⅱ聚煤作用最强。

     

    Abstract: In order to investigate the coal accumulation pattern under the time-equivalent stratigraphic framework for the Carboniferous and Permian coal measures in Shanxi Province, this paper analyzed the lithofacies of coal-bearing searies association based on the outcrops and borehole data, and also drawn the contour maps of stratalisopachs, percentages of limestones, sandstone to mudstone thickness ratios,and coal thickness. The study results showed that four depositional systems were identified, including carbonate platform-barrier-lagoon, delta, fluvial, and lacustrine systems, the three third-order sequences were subdivided for Benxi,Taiyuan,and Shanxi Formations, and also the sequence-based Palaeogeography maps were reconstructed with the major Palaeogeographical units including fluvial plain, delta, barrier island, tidal-lagoon, and carbonate shelf. Transgression direction changed from the northeast in Sequence I into the southeast in Sequences II and III.The coals in Sequence I were mainly formed in the tidal-lagoon environment, while the coals in Sequences II and III were formed in the delta plain environment, meanwhile from Sequence I though Sequence III,the coal-accumulating center migrated from north to south,specifically coals were well developed in Sequence II.

     

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