新疆阿合奇地区哈拉奇组、康克林组碳酸盐岩微相特征和沉积环境

    Carbonate microfacies characteristics and sedimentary environment of Karaqi Formation and Kangkelin Formation in Akqi area, Xinjiang

    • 摘要: 采用微相分析的方法,对新疆阿合奇地区晚石炭世—早二叠世哈拉奇组和康克林组碳酸盐岩的微相类型和沉积环境进行了研究,发现两地层单元具有不同的岩石结构、颗粒组分及生物化石组合微相特征。哈拉奇组沉积粒度相对较细,泥质含量较高,生物碎屑相对较少,可划分出5种微相类型和5种次一级微相类型;康克林组生物种类丰富,个体保存较完整,颗粒组分出现了较多鲕粒、核形石等,亮晶胶结普遍,泥级组分相对较少,可划分出6种微相类型和8种次一级微相类型。根据微相类型组合特征和野外沉积构造,认为哈拉奇组碳酸盐岩主要形成于深水陆棚和台地斜坡2种沉积环境,其次为台地边缘浅滩和开阔台地沉积,总体反映较深水沉积环境;康克林组碳酸盐岩主要形成于台地边缘浅滩、开阔台地和局限台地3种沉积环境,反映沉积环境水体相对较浅。

       

      Abstract: Using the microfacies analysis method, the authors studied microfacies types and depositional environment of carbonate rocks during Late Carboniferous-Early Permian Karaqi Formation and Kangkelin Formation from Akqi, Xinjiang. The two stratigraphic units have many differences in rock textures, granular components and fossil assemblages. The Karaqi Formation sediments have finer granularity, higher content of argillaceous materials and less bioclast matter, and can be divided into five microfacies types and five secondary microfacies types. The sediments of Kangkelin Formation have abundant organic species, complete individuals and lower content of argillaceous materials, and its grains contain lots of oolites, oncolites etc. This formation can be divided into six microfacies and eight secondary microfacies. According to the field sedimentary structure and assemblage characteristics of microfacies types, Karaqi Formation carbonate rocks are considered to have been mainly formed in basin margin and platform slope, followed by platform margin shoal and open platform, suggesting a deep water environment. The Kangkelin Formation carbonate rocks were mainly formed in platform margin shoal, open platform and restricted platform, implying a relatively shallow sedimentary environment.

       

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