泥质岩定义及分类问题的探讨  

Discussion on definition and classification of mudrock

作　　者：邵龙义[1] 张天畅 SHAO Longyi;ZHANG Tianchang(College of Geoscience and Surveying Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)地球科学与测绘工程学院,北京100083

出　　处：《古地理学报》2023年第4期742-751,共10页Journal of Palaeogeography：Chinese Edition

基　　金：山西省科技计划揭榜招标项目(编号:20201101004);国家自然科学基金面上项目(编号:41572090);中国矿业大学(北京)越崎学者A类资助共同资助。

摘　　要：泥质岩为细粒沉积岩的主要类型,但国内外对其概念及分类有多种不同的理解,这给学术研究带来诸多困扰。文中梳理了国内外沉积学发展中泥质岩相关概念和定义的变迁,并试图建立一个实用的泥质岩(mudrock)分类体系。欧美国家多倾向于使用“泥质岩”一词,用于指粒径小于0.063 mm的细粒陆源碎屑岩,包括粉砂岩(粉砂含量大于2/3)、泥岩(粉砂和黏土含量都不超过2/3)和黏土岩(黏土含量超过2/3),其中发育纹层的岩石称为页岩;而前苏联学者则倾向于使用“黏土岩”一词,用于指黏土矿物含量大于50%的沉积岩,其中可劈裂成薄层的岩石称为页岩。国内外泥质岩及细粒沉积岩分类命名主要依据结构(粒级)、成分和沉积构造等特征,目前分类方案主要有2种,一种是多要素岩石综合分类方案,另一种是端元图式分类方案。笔者建议采用“泥质岩”一词作为细粒陆源沉积岩(物)的总称,指示主要由粒径0.004~0.063 mm的粉砂和小于0.004 mm的黏土组成的细粒陆源沉积岩;采用三棱柱图解分类方法,以碎屑矿物(主要是长英质碎屑矿物)、黏土矿物和内源矿物为三端元,划分出细粒陆源沉积岩(泥质岩)和细粒内源沉积岩2个大类,前者可进一步分为粉砂岩、泥岩和黏土岩3个亚类,若具纹层和页理构造则称为页岩;并以TOC含量0.5%和2.0%为界,将细粒陆源沉积岩划分为贫有机质、含有机质和富有机质3类。期望该分类方案能够对泥质岩行业分类方案制定起到推动作用。Mudrock is a major category of fine-grained sedimentary rocks,and there have been different understandings of its definition and classification in China,resulting in much confusion for academic research.This paper reviews the evolution of mudrock-related concepts and definitions in the development of sedimentology at home and abroad and attempts to provide a practical classification system for mudrock.Scholars in European and American tend to use the term“mudrock”,which refers to fine-grained terrestrial clastic rocks with a grain size less than 0.063 mm,including siltstone(two-thirds or more silt content),mudstone(neither silt nor clay content greater than two-thirds)and claystone(more than two-thirds clay content),in which the laminated rock is called shale.However,scholars in the former Soviet Union tend to use the term“глинистыепороды”(argillaceous rock)to refer to sedimentary rocks containing more than 50%of clay minerals,in which the fissile rock is called shale.There are essentially two classification schemes for mudrock and other fine-grained sedimentary rocks,classified by texture(grain size),composition and sedimentary structure.One is a multi-element comprehensive rock classification,and the other is an end-members diagrammatic classification.We recommend the term“mudrock”as a general name for the fine-grained terrestrial sedimentary rocks consisting mainly of silt-sized(0.004-0.063 mm)and clay-sized(less than 0.004 mm)clasts.A triangular prism diagram classification method is adopted to classify fine-grained sedimentary rocks into fine-grained terrestrial sedimentary rock(i.e.mudrock)and fine-grained endogenous sedimentary rock,based on three end-elements of detrital minerals(mainly felsic detrital minerals),clay minerals and other endogenous minerals.Mudrock is further classified into three subgroups of siltstone,mudstone and claystone,or“-shale”if laminations or fissility are developed.Taking the TOC contents of 0.5%and 2%as the dividing points,fine-grained sedimentary

关 键 词：泥质岩 泥岩 页岩 粉砂岩 黏土岩 分类命名 

分 类 号：P588.22[天文地球—岩石学]