| 泥岩与页岩特征辨析 |
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| 引用本文： | 蔡毅,朱如凯,吴松涛,刘畅.泥岩与页岩特征辨析[J].地质科技通报,2022,41(3):96-107. |
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| 作者姓名： | 蔡毅 朱如凯 吴松涛 刘畅 |
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| 基金项目： | 国家自然科学基金重大项目“陆相页岩油富集主控因素与有利区带评价方法”42090025中国石油天然气股份有限公司科学研究与技术开发项目“中国陆相页岩油成藏机理、分布规律与资源潜力研究”2019E-2601 |
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| 摘 要： | 细粒沉积岩类型复杂，原因是其定义基于结构粒度概念，缺乏对矿物成分的有效约束，加之，不同学者是在不同尺度下对构造现象进行描述，使得细粒沉积岩缺乏较为科学、系统的分类。为辨析泥岩与页岩的特征，通过大量调研国内外沉积学教材及相关文献发现:细粒沉积物(粒径小于62.5 μm)的概念自20世纪30年代进入人们的视野，后被广大研究人员广泛接受，且大多数学者普遍认为可依据粒度大小，进一步将细粒沉积物划分为黏土级颗粒(粒径小于3.9 μm)和粉砂级颗粒(粒径介于3.9~62.5 μm之间)。但是，国、内外沉积学界对细粒沉积物“泥”(泥级颗粒)的粒径划分不同，欧美学者一般将“泥”界定为粒径小于62.5 μm，包括黏土级颗粒与粉砂级颗粒。在我国，自20世纪50年代开始，沿用了前苏联的方案，“泥”的粒径对应黏土级颗粒即小于3.9 μm，这一分歧是导致泥岩与页岩等概念使用混乱的根本原因。概而言之，固结的泥岩具有与页岩相同的粒级结构和组分，但是不具备页岩的“纹层”或“页理”构造特征；辩证而言，“纹层”强调沉积过程所形成的垂向层理差异，而“页理”则是成岩过程受风化作用影响形成的力学薄弱面。从泥岩和页岩的矿物组成看，存在石英和长石硅质矿物、黏土矿物，碳酸盐矿物的混合沉积作用的影响，需要从沉积成因出发，结合构造特征，综合矿物类型、有机质丰度和颗粒来源等因素对泥岩和页岩进行岩性岩相分类。实践表明，页岩油气的开发动用需要地质工程一体化协同，辨析泥岩和页岩的特征差异性对产层优选具有重要意义。
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| 关 键 词： | 泥岩 页岩 纹层 页理 细粒混合沉积 页岩油气 |
| 收稿时间： | 2021-07-08 |
Discussion on characteristics of mudstone and shale |
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| Abstract: | The types of fine-grained sedimentary rocks are complicated because their definition is based on the concept of texture grain size, which lacks effective constraints on mineral composition; In addition, different scholars have described the fabric phenomena at different scales, which altogether mades fine-grained sedimentary rocks lack of scientific and systematic classification. To analyse distinguish the characteristics of mudstones and shales, a large number of investigations and surveys were conducted in the textbooks of sedimentology and related literature at home and abroad. It is found showing that since the conception of fine-grained sediments (size less than 62.5 μm) appeared in the 1930s, it was accepted widely by the researchers, and based on particle size, most scholars generally appreciated it that the fine-grained sediments could further be divided into clay grains (size less than 3.9 μm) and silt grains (size between 3.9 μm and 62.5 μm). However, domestically and internationally, the particle size of fine-grained sediment "mud" (mud grains) was divided differently. Generally, scholars in Europe and America defined the mud as a particle size less than 62.5μm, including clay and silt grains. In our country, the particle size of mud corresponded to that of clay grains, which was less than 3.9μm, mainly following the former Soviet Union′s sedimentary scheme, since the 1950s. This divergence is also the fundamental reason for the confusion of concepts. In general, the consolidated mudstone has the same grain size structure and composition as shale, but does not have the "lamination" or "fissile" structural characteristics of shale. Dialectically speaking, "lamination" emphasizes the stratigraphic vertical differences formed by sedimentary processes, while "fissile" refers to the mechanical weaknesses formed by weathering during diagenetic processes. In terms of the mineral composition of mudstone and shale, there are fine-grained mixed sedimentation effects of quartz and feldspar siliceous minerals, clay minerals and carbonate minerals. Therefore, it is necessary to comprehensively classify fine-grained sediments into lithologies and lithofacies based on sedimentary genesis, combined with structural characteristics, mineral types, abundance of organic matter, and particle sources comprehensively. Practice has shown that the development and utilization of shale oil and gas require the integration of geology and engineering, and distinguishes the difference in characteristics of mudstone and shale is of great significance to the optimization of pay zones. |
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