Depositional Markers of Marine Transition Facies and Its Evolution of Member 1 of Shanxi Formation, Tabamiao Area, North Ordos Basin
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摘要: 鄂尔多斯盆地塔巴庙地区在上石炭统太原组到下二叠统山西组沉积过程中经历了潮坪、泻湖—海陆过渡三角洲演化过程。在这一演化过程中山西组一段沉积环境前人研究后得出了不同的结论，有的认为属于陆相湖泊三角洲沉积，有的认为是海陆过渡三角洲沉积，还有的认为是湖泊三角洲，但受到间歇性海侵影响。在前人大量研究基础上，通过详细的岩心观察和岩石学特征的分析，在山西组一段发现了代表海相或海陆过渡环境沉积的典型特征，分别为①成分成熟度和结构成熟度均高的石英砂岩、②泥晶菱铁矿岩、③海百合、有孔虫骨屑泥岩、④铝土矿质泥岩和⑤粉晶白云岩。上述海相环境标志的存在，充分说明塔巴庙地区山西组一段沉积期为海相或海陆过渡沉积环境。在上述基础上讨论了山西组一段沉积环境的时空演化特点。Abstract: Tabamiao area of Ordos basin from Taiyuan Formation in Upper Carboniferous to Shanxi Formation in Lower Permian underwent a prograding sedimentary evolution process, i.e. from tidal flat to lagoon marinecontinental transition delta. Previous studies drew different conclusions after studying the depositional environmental of member 1 of Shanxi Formation during the evolution. Some think it was the lake delta of the terrestrial facies, others believe that it was the deposition of marinecontinental transition delta,or the lake delta but influenced by the intermittent transgression. This paper, based on previous data, detailed core observation and petrology features, puts forward that member 1 of Shanxi Formation represents marine facies or the marinecontinental transition depositional environment, such as ①high maturity of the component and texture squartz-sandstone, ②micrite siderite stone, ③sea lily, foraminifer mudstone，④bauxite mudstone and ⑤crystal powder dolomite. Those marine facies depositional environmental features prove the depositional process of Tabamiao area member 1 of Shanxi formation is marine facies or marinecontinental transition depositional environment. Authors also discussed the spatialtemporal evolution characteristics of member 1 of Shanxi Formation depositional environment.
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Key words:
- Tabamiao area /
- member 1 of Shanxi Formation /
- environmental feature /
- evolution
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