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现代地质 ›› 2025, Vol. 39 ›› Issue (02): 294-311.DOI: 10.19657/j.geoscience.1000-8527.2024.075

• 地层、古生物与古环境 • 上一篇    下一篇

豫西中元古界龙家园组一段硅质岩成因及环境响应

李倩倩(), 郑德顺(), 孙风波, 王昕   

  1. 河南理工大学资源环境学院,河南 焦作 454000
  • 出版日期:2025-04-10 发布日期:2025-05-08
  • 通信作者: 郑德顺,男,教授,博士生导师,1977年出生,地质资源与地质工程专业,主要从事构造-沉积响应的教学研究工作。Email:zhengdeshun@126.com
  • 作者简介:李倩倩,女,博士研究生,1990年出生,地质资源与地质工程专业。Email:lqianqianlucky@163.com
  • 基金资助:
    国家自然科学基金项目(42172131)

Genesis and Environmental Response of Siliceous Rocks in the First Member of Longjiayuan Formation of Mesoproterozoic, Western Henan

LI Qianqian(), ZHENG Deshun(), SUN Fengbo, WANG Xin   

  1. School of Resources and Environment, Henan Polytechnic University, Jiaozuo, Henan 454000, China
  • Published:2025-04-10 Online:2025-05-08

摘要: 不同地质历史时期硅质岩发育成因复杂,其硅质来源受到微生物、陆源碎屑、海水条件、火山热液等多种因素影响,硅质岩对构造演化阶段沉积环境具有重要的指示意义。前寒武纪海洋中溶解二氧化硅浓度较高,但所涉及的二氧化硅来源和硅质沉积物的形成过程,以往研究对华北克拉通南缘硅质岩认识较少。豫西中元古界官道口群龙家园组一段硅质岩类型多样,发育连续。本文基于其岩石学特征,结合主微量元素分析,对龙一段硅质岩的硅质来源、形成过程及其机制等进行研究。结果表明:龙一段硅质岩在剖面上均匀分布,按形态可分为纹层-条带状、变形层状、结核-团块状和菊花状。地球化学组分中Al/(Al+Fe+Mn) 值判别图解及Ce/Ce*、Eu/Eu*值综合分析硅质组分具有热液与海洋溶解硅的两种来源。硅质岩经历了沉积期、早成岩期和成岩期三个阶段形成过程:在沉积期阶段,海水中的硅质组分主要以硅质胶体形式沉积;在早成岩期阶段,尚未固结的硅质沉积物在重力作用下聚集于低洼地带,并在风暴等外力作用下形成一些风暴成因硅质岩;在成岩期阶段,硅质沉积物受到成岩压实作用逐渐固结,地形平缓处形成层状硅质岩,在低洼处形成团块状硅质岩。龙家园组一段硅质岩记录了中元古代华北克拉通南缘的沉积环境特征,指示该时期豫西地区处于相对开放的浅海环境,沉积环境稳定,有利于硅质的富集与保存。

关键词: 硅质岩, 硅质来源, 硅质岩成因, 豫西地区, 中元古界

Abstract:

Siliceous rocks in different geological periods have complex genesis, and their sources of silica are influenced by various factors such as microorganisms, terrestrial debris, seawater conditions, and hydrothermal fluids.Siliceous rocks serve as important indicators of sedimentary environments at different stages of tectonic evolution.The concentration of dissolved form of silicic acid is high in the Precambrian ocean, but the silica source of the siliceous rocks and the formation process of siliceous sediments in the southern margin of the North China Craton have not been extensively studied.The siliceous rocks of the first member of the Longjiayuan Formation in the Mesoproterozoic Guandaokou Formation in Western Henan are of various types and show continuous development.Based on their petrological characteristics and combined with analyses of major and trace elements, the silica sources, formation processes, and mechanisms of the Longjiayuan siliceous rocks were studied.The results show that the Longjiayuan siliceous rocks are uniformly distributed in the section and can be classified into bedding-banded, deformed stratified, nodule-massive, and chrysanthemum-like forms.Geochemical analyses including discriminant diagrams of Al/(Al+Fe+Mn) values as well as Ce/Ce* and Eu/Eu* values suggest two sources of silica components: hydrothermal and dissolved silica from seawater.The formation process of the siliceous rocks can be divided into three stages: sedimentary, early diagenetic, and diagenetic stages.During the sedimentary stage, silica components in seawater are mainly deposited in the form of siliceous colloids.During the early diagenetic stage, unconsolidated siliceous sediments aggregate in low-lying areas under the influence of gravity, forming some storm-induced siliceous rocks under the action of external forces such as storms.During the diagenetic stage, siliceous sediments are gradually consolidated under the pressure of diagenesis, forming layered siliceous rocks in gently sloping areas and massive siliceous rocks in low-lying areas.The siliceous rocks of the first member of the Longjiayuan Formation record the Mesoproterozoic sedimentary environment of the southern North China Craton, indicating a stable, open shallow marine setting in western Henan, conducive to silica enrichment and preservation.

Key words: siliceous rock, siliceous source, siliceous rock genesis, Western Henan, Mesoproterozoic

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