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    内蒙古大青山地区中侏罗世古气候分析

    A palaeoclimatic analysis of the Middle Jurassic period in Daqinshan area, Inner Mongolia

    • 摘要: 提要:对内蒙古中部大青山地区石拐子侏罗纪陆相含煤沉积断陷盆地的侏罗系召沟组植物化石进行系统分类、鉴定与研究。结果表明召沟组植物群共有18 属31 种,分别属于真蕨纲、苏铁纲、银杏纲、茨康纲、松柏纲(Filicopsida, Cycadopsida, Ginkgopsida, Czekanoskiopsida, Coniferopsida)。同时利用扫描电镜(SEM),对银杏纲和茨康纲化石表皮细胞的种类、形态及构造特点进行形态解剖学研究。研究认为,召沟组植物群是一个属于中国北方区以Coniopteris- Phoenicopsis为代表的晚期组合(即中侏罗世组合)。该植物群的发现揭示石拐子盆地中侏罗世为温暖潮湿气候环境下的湖泊沼泽沉积环境,这种沉积环境有利于该区煤炭、石油和天然气的形成。这项工作对于区域盆地演化和其中能源矿产的成因研究及预测具有重要的指导意义。

       

      Abstract: Abstract:Using traditional means, the authors recognized 18 genera and 31 species from plant fossils of Jurassic Zhaogou Formation in Shiguaizi Basin of Daqingshan area, a typical Jurassic continental facies coal-bearing faulted subsidence basin developed in central Inner Mongolia. These genera and species belong to Filicopsida, Cycadopsida, Ginkgopsida, Czekanoskiopsida, Coniferopsida respectively. Meanwhile, based on features of the plant fossil assemblage, the authors carried out a series of anatomic studies by using advanced SEM to probe into the type, morphology and textures of the surface cells of the Ginkgopsida and Czekanoskiopsida. It is held that the plant fossils in Zhaogou Formation belong to a late assemblage (i.e., the Middle Jurassic assemblage) represented by the Coniopteris- Phoenicopsis in North China. The discovery of the assemblage suggests that the Shiguaizi Basin was under a warm and wet swamp and lake environment during Middle Jurassic, and such an environment was favorable for the formation of coal, oil and natural gas. The result obtained by the authors is helpful to the study of the evolution of the basins and to the genetic research and prediction of fossil mineral resources in this area.

       

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