山东莱芜九龙山寒武纪张夏组核形石灰岩分类及沉积环境探讨

Study on Classification and Depositional Environment of Nuclear Limestones in Cambrian Zhangxia Formation in Jiulongshan of Laiwu City in Shandong Province

摘要:

核形石灰岩作为微生物岩的一种重要类型，长期受到地质学家的广泛关注；近年来，随着研究的不断深入，有关核形石灰岩分类、沉积环境等的探讨再次成为沉积学研究的热点。通过野外观察描述与室内镜下分析相结合，对山东莱芜九龙山寒武纪张夏组产出的核形石灰岩进行系统研究。根据核形石灰岩的宏观特征、共生组分及其含量等特征，将该地区产出的含核形石的灰岩分为：生屑质核形石灰岩、含生屑核形石灰岩、含核形石生屑灰岩与含核形石鲕粒灰岩4类，同时对4种含核形石灰岩的沉积环境进行系统分析，主要为潮下低能带与潮下高能带，并简要分析了该地区核形石灰岩的形成过程。

Abstract:

Nuclear limestone is an important type of microbial carbonates, which receive a broad attention of geologists. Recently, classification and depositional environments study of nuclear limestone has become one of popular subject in carbonate sedimentology. Based on detailed field observation and microscopic analysis, nuclear limestone in Cambrian Zhangxia formation in Jiulongshan section in Shandong province has been studied systematically in this paper. According to macroscopic characteristics, paragenetic component and contents, nuclear limestones in this area can be classified into four types, they are bioclastic oncolite, oncolite with bioclasts, bioclastic limestone with oncoids and oolitic limestone with oncoids. The depositional environments of the four types of Nuclear limestones have been analyzed comprehensively. They are generally deposited in subtidal zones with either low-energy or high-energy zones. The formation environment of core limestone in this area has been analyzed as well.