| 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 |
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| 关键词:Permian Maokou Formation chert events silicon isotope genesis research Zunyi in northern Guizhou |
| 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) |
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| The Determination of Silicon Source of Large-scale Chert Events during the Permian Guadalupian–Lepingian Transition Period in Northern Guizhou Province |
| 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. |
| YE Yuan-mou,FU Yong,JIANG Ran,QIAO Wen-lang,LONG Xuan-lin.2020.The Determination of Silicon Source of Large-scale Chert Events during the Permian Guadalupian–Lepingian Transition Period in Northern Guizhou Province[J].Acta Geoscientica Sinica,41(5):699-713. |
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