【摘要】 采用微相分析的方法,对北京西山下苇甸剖面中寒武统碳酸盐岩的生物组合、颗粒成分、基质类型及其结构等微相特征做了深入研究,区分出8种碳酸盐岩微相类型,即微角砾状生屑-岩屑泥粒灰岩,异地生屑泥粒—粒泥灰岩,含包壳鲕粒和磨圆生屑的泥粒—粒泥灰岩,含包壳鲕粒的颗粒灰岩,海百合茎泥粒灰岩,同心圆鲕粒颗粒灰岩,泥晶鲕粒颗粒—泥粒灰岩,放射鲕粒颗粒—泥粒灰岩。8种微相类型在中寒武统剖面上不等同出现构成了代表两次海平面下降—上升的演化过程,即由徐庄组下部的开阔台地相开始,向上至徐庄组上部变化为滩前斜坡相,张夏组下部又返回至开阔台地相,最后在张夏组上部又以滩前斜坡相告终。更多还原

【Abstract】 By means of microfacies analysis,this paper studies in detail the grain composition,the types and texture of the matrix,the microfacies characteristics of the carbonate rocks of Middle Cambrian of Xiaweidian profile in Western Hills,Beijing.The Middle Cambrian carbonate rocks in the studied profile can be mainly divided into eight microfacies types,including microbreccia bioclastic-lithoclastic packstone,allochthonous bioclastic packstone and wackstone,packstone and wackstone with coated micrite ooids and abraded bioclastic,grainstone with coated micrite ooids,crinoids packstone,ooid grainstone with concentric ooids,grainstone and packstone with micrite ooids,grainstone and packstone with radial ooids.Analysis of all the microfacies reveals that the Middle Cambrian of the studied profile had experienced two sedimentary facies sequences of sea level rise.One of the sedimentary facies sequences starts from an open marine facies of the lower part of Xuzhuang Formation,and gradually evolves upwards to a slope facies of the shoal front of the upper part of Xuzhuang Formation.The others develop from an open marine facies of the lower part of Zhangxia Formation to a slope facies of the shoal front of the upper part of Zhangxia Formation.更多还原