| 黔北瓜德鲁普世—乐平世转换时期大规模成硅事件硅质来源厘定 |
| 点此下载全文 |
| 引用本文：叶远谋,付勇,江冉,谯文浪,龙宣霖.2020.黔北瓜德鲁普世—乐平世转换时期大规模成硅事件硅质来源厘定[J].地球学报,41(5):699-713. |
| DOI：10.3975/cagsb.2020.072602 |
| 摘要点击次数: 1924 |
| 全文下载次数: 1547 |
|
| 基金项目:中国地质调查局中国矿产地质志项目(编号: DD20160346; DD20190379);国家重点研发计划项目(编号: 2017YFC0602701);贵州大学引进人才科研项目(编号: 贵大人基合字(2016)82号);贵州大学2017年度学术新苗培养及创新探索专项(编号: 黔科合平台人才［2017］7285);贵州省创新人才基地项目(编号: RCJD-2018) |
|
| 中文摘要:联合古陆(Pangea)大陆边缘及泛大洋和古特提斯洋的广大地区在二叠纪时期出现大规模硅质富集事件, 被称之为“全球二叠纪硅质沉积事件”。黔北遵义地区二叠纪瓜德鲁普世—乐平世转换时期成硅事件为该事件重要组成部分, 呈现出“白泥塘层”层状炭硅质灰岩、层状硅质岩和硅质条带或燧石结核三种不同类型硅质富集岩石。遵义地区硅质来源的研究能够深入认识全球性“二叠纪硅质沉积事件”, 同时为研究该时期遵义盆地的结构和演化提供了重要窗口, 对遵义锰矿成矿作用也有重要指示意义。文中采用岩石学和地球化学方法并通过硅同位素的协同指示意义对硅质来源进行厘定, 并对硅质岩成因与沉积环境进行归纳总结, 在研究区建立系统完整的硅质富集沉积体系。实验测试结果显示: “白泥塘层”炭硅质灰岩中δ30Si值介于–0.09 ~ –0.67之间, 层状硅质岩中δ30Si值介于0.03~1.47之间。结合主、微量元素特征和岩石学特征表明: “白泥塘层”炭硅质灰岩形成于深水盆地缺氧还原环境, 硅质来源于海底热液, 沉积中心位于热液喷口的附近, 沉积过程中受陆源硅质输入影响显著。层状硅质岩形成于浅海台地正常沉积氧化环境, 硅质来源于海底热液, 沉积远离热液喷口, 热液沿构造裂隙通道经过了一定的迁移距离, 与茅口组浅海台地相正常沉积的块状-厚层状灰岩发生交代作用, 从而形成硅质岩; 硅质条带或结核形成于浅海台地正常沉积氧化环境, 硅质主要来源于海底热液, 沉积过程中有陆源硅质的输入, 由长时间多期次的海底热液喷流作用带来的硅质迁移至盆地外围浅海台地形成。 |
| 中文关键词:二叠纪 茅口组 成硅事件 硅同位素 成因研究 黔北遵义 |
| |
| The Determination of Silicon Source of Large-scale Chert Events during the Permian Guadalupian–Lepingian Transition Period in Northern Guizhou Province |
|
|
| Abstract:A large-scale siliceous enrichment event occurred during the Permian period on the continental margin of the United Paleoea (Pangea) and in the Pan-Ocean and Gutti Ocean, which is called the “global Permian Chert Event”. The chert event during the Permian Guadalupian–Lepingian transition period in the Zunyi area of northern Guizhou was an important part of this event, presenting three different types of siliceous enriched rocks, i.e., the “Bainitang layer” bedded carbon siliceous limestone, the bedded siliceous rocks and the siliceous bands or nodular cherts. The study of siliceous sources in the Zunyi area can provide a deep understanding of the global “Permian siliceous sedimentary events”. It also provides an important window for studying the structure and evolution of the Zunyi Basin during this period, and also has important implications for the mineralization of the Zunyi manganese deposit. In this paper, petrological and geochemical methods were used to determine the source of siliceous materials through the synergistic indication of silicon isotopes. The genesis and depositional environment of siliceous rocks were summarized and a systematic and complete siliceous enrichment deposition system was established in the study area. Experimental test results show that the δ30Si value in the “Bainitang layer” carbon siliceous limestone is between –0.09 and –0.67, and the δ30Si value in the bedded siliceous rock is between 0.03 and 1.47. Combining the characteristics of main and trace elements and petrology shows the following features: The “Bainitang layer” carbon siliceous limestone was formed in the hypoxic-reducing environment of deep-water basins; siliceous was derived from submarine hydrothermal fluids; the deposition center was located near the hydrothermal vents; the deposition process was significantly affected by terrestrial silica input; the bedded siliceous rocks were formed in the normal sedimentary and oxidizing environment of shallow sea platforms; silicon sourcesa were derived from submarine hydrothermal fluids; the deposition was far away from the hydrothermal vents; the hydrothermal fluid had moved a certain distance along the structural fracture channel; siliceous rock was formed by metasomatism of deposited massive-thick bedded limestone of the Maokou Formation; siliceous bands or nodular cherts were formed in the normal sedimentary oxidation environment of shallow sea platforms; siliceous mainly came from submarine hydrothermal fluids; there was a terrestrial silicon input during the deposition process, and the input of siliceous material was formed by the migration of the siliceous material brought by long-term and multi-stage submarine hydrothermal jets to the shallow offshore platform in the periphery of the basin. |
| keywords:Permian Maokou Formation chert events silicon isotope genesis research Zunyi in northern Guizhou |
| 查看全文 查看/发表评论 下载PDF阅读器 |
|
|
|
|
|
