重庆城口震旦系下统陡山沱组沉积体系研究

Study on Lower Sinian Doushantuo Formation Sedimentary System in Chengkou,Chongqing

重庆城口震旦系下统陡山沱组共分两段:第一段岩性为黑色砂质页岩与粉砂岩互层,下部砂质成分增多;第二段顶部为锰矿层,锰矿层之下为黑色炭质页岩及黑色泥质页岩。在野外剖面、钻孔岩心宏观、微观沉积相分析的基础上,并结合剖面结构和区域资料的分析,归纳出研究区震旦系下统陡山沱组发育浅海陆棚沉积相,包括过渡和滨外陆棚两个微相,其中过渡微相主要为陡山沱组第一段下部,无菱锰矿赋集,滨外陆棚微相主要位于陡山沱组第二段,为菱锰矿的主要赋集层位,多为鲕状、球状以及条带状。

The lower Sinian Doushantuo Formation in Chengkou, Chongqing can be subdivided into two members. The lithologie associ- ation of the first member is interbedded black arenaceous shale and siltstone, while in its lower part arenaceous material increased; the top of the second member is manganese ore, while black carbonaceous shale and black argillaceous shale under. Based on field obser- vation, drilling core macroscopic and microscopic sedimentary facies analyses, combined with section configuration and regional data a- nalysis, have generalized that in the Doushantuo Formation developed shallow sea shelf sedimentary facies, including transitional and offshore shelf two microfacies. In which, the transitional microfacies is mainly in the lower part of the first member, without rhodoehro- site enrichment; offshore shelf microfacies is mainly in the second member, that is the main horizon of rhodochrosite enrichment, with mostly oolitic, spherical and banded structures.