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。

关键词: 泥质岩, 泥岩, 页岩, 粉砂岩, 黏土岩, 分类命名

Abstract: 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 “глинистые породы” (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 rocks are classified into organic-poor,organic-bearing,and organic-rich ones. It is expected that this classification scheme will contribut to the mudrock classification.

Key words: mudrock, mudstone, shale, siltstone, claystone, classification and nomenclature

中图分类号: 

• P588.22