江西丰城天然微纳米硅碳矿床Re-Os同位素定年研究  

Re-Os Isotope Dating of the Natural Micro/Nano Silicon-Carbon Deposit in Fengcheng City,Jiangxi Province

作　　者：万新 王先广 胡正华 肖玉如 胡秋萍 施鹏超 张永文 冯增会 WAN Xin;WANG Xianguang;HU Zhenghua;XIAO Yuru;HU Qiuping;SHI Pengchao;ZHANG Yongwen;FENG Zenghui(Jiangxi Mineral Resources Guarantee Service Center,Nanchang 330025,China;Jiangxi Institute of Land and Space Survey&Planning,Nanchang 330025,China;Brigade of Energy Geology,Jiangxi Bureau of Geology,Nanchang 330008,China;Jiangxi Geological Survey and Exploration Institute,Nanchang 330001,China)

机构地区：[1]江西省矿产资源保障服务中心,江西南昌330025 [2]江西省国土空间调查规划研究院,江西南昌330025 [3]江西省地质局能源地质大队,江西南昌330008 [4]江西省地质调查勘查研究院,江西南昌330001

出　　处：《岩矿测试》2023年第6期1078-1089,共12页Rock and Mineral Analysis

基　　金：江西省地质勘查基金项目(20170041,JXKB-K202201);江西省科技厅科技专项资助项目(20103AE191004)。

摘　　要：江西省丰城石炉坑天然微纳米硅碳矿床为全球首例由植硅石成矿的沉积矿床,矿床的开发对信息技术、新能源、新材料、高端制造等战略性新兴产业具有关键作用,硅碳矿在分布范围、成因类型、资源类型等方面与石英、石墨不同,作为新矿种开展研究特别是年代学研究具有重要意义。在富有机质沉积岩定年研究中,Re-Os同位素定年作为一种强有力的测试手段,其应用多集中在海相沉积岩,而湖相沉积岩受物源、地质作用、陆源碎屑物质等多种因素影响则少见成功报道。为精确厘定石炉坑硅碳矿床的成矿时代,本文尝试利用Re-Os同位素测试对矿区石炉坑组下段7件植硅石岩进行定年研究,获得植硅石岩的Re-Os同位素年龄为43.1±3.7Ma(n=7,MSWD=6.2),直接指示了石炉坑植硅石岩成岩成矿时代为古近纪始新世。研究表明,植硅石岩中Re/Os高分异(均值525.1)与其沉积环境、生物沉积作用有关。187Os/188Os较高的初始值(1.713±0.0036)则受沉积环境、区域岩石及构造运动共同影响。本研究成果体现了Re-Os同位素体系对湖相沉积岩测年研究的适用性。BACKGROUND:The micro/nano silicon-carbon deposit in Fengcheng City,Jiangxi Province,is the first sedimentary deposit mineralized by phytoliths in the world.According to the research carried out here,micro/nano silicon-carbon ore may have been formed by the long-term accumulation and consolidation of phytoliths.In terms of distribution range,genetic type and resource type,the micro/nano silicon-carbon deposit has many new features.Therefore,considering the particularity of the deposit,it is of great significance to carry out research,especially chronological research.Moreover,Re-Os isotope system of organic-enriched sedimentary rocks has been applied to directly dating deposition ages or stratigraphic boundary age,which has made many achievements in chronological research.However,most of the studies focus on marine sediments samples,while lacustrine sediments samples are rarely affected by many factors,such as provenance,geological processes,and terrigenous clastic materials.OBJECTIVES:To accurately determine the mineralization age of the natural micro/nano silicon-carbon deposit.METHODS:Re-Os isotope testing was used to date the phytolith rock samples(lacustrine sediment samples)in the lower section of the Shilukeng Formation in the mining area.Isotope ratios were determined by NTIMS,and GBW04477(JCBY)was used as the reference material.RESULTS:The Re-Os isotope age of the samples is 43.1±3.7Ma(n=7,MSWD=6.2)which directly defines the diagenetic mineralization age of phytolith rock of the deposit.The high 187Re/188Os value of the samples is closely related to the sedimentary environment and the origin of biological sedimentation.The high initial 187Os/188Os ratio may be related to tectonic movement events,high Os content and migration rate of adjacent strata.The study shows that Re and Os isotopes are adsorbed and sealed in phytolith with organic carbon in the process of enrichment.Owing to the phytolith’s stable silica structure,high temperature resistance and corrosion resistance,the Re-Os isotope system has a

关 键 词：石炉坑矿区 RE-OS同位素 成矿时代 微纳米硅碳矿 植硅石 

分 类 号：O659.63[理学—分析化学]