岩矿测试2023，Vol.42Issue(6)：1078-1089,12.DOI:10.15898/j.ykcs.202302020013
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
摘要
Abstract
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 good sealing property in it.Protected by the special structure,the organic carbon in phytolith mainly exists in the tiny cavity of phytolith,and the organic carbon has not been exchanged with the outside world due to its storage,which provides favorable conditions for dating.Moreover,the large amount of phytolith in the samples also provides favorable conditions for the enrichment of Re and Os isotopes. CONCLUSIONS:The results of this study provide for the determination of sedimentary age about lacustrine sediments samples by the Re-Os isotope analysis.It is important to strengthen research about the study of Re-Os enrichment mechanism by micro/nano silicon-carbon ore samples.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Key words
Shilukeng mining area/Re-Os isotope/metallogenic age/micro/nano silicon-carbon deposit/phytolith分类
化学化工引用本文复制引用
万新,王先广,胡正华,肖玉如,胡秋萍,施鹏超,张永文,冯增会..江西丰城天然微纳米硅碳矿床Re-Os同位素定年研究[J].岩矿测试,2023,42(6):1078-1089,12.基金项目
江西省地质勘查基金项目(20170041,JXKB-K202201) （20170041,JXKB-K202201）
江西省科技厅科技专项资助项目(20103AE191004) （20103AE191004）
