矿床地质2012，Vol.31Issue(2)：241-254,14.
江西广丰杨村超大型滑石矿床成因探讨
Genesis of Yangcun superlarge talc deposit in Guangfeng County, Jiangxi Province
摘要
Abstract
The Yangcun talc deposit in Guangfeng County of Jiangxi Province is one of the superlarge talc deposits in the world. The ore reserves are over a hundred million tons. The talc ore consists mainly of oolite granular talc with a small amount of quartz, carbonates and disseminated organic matter, assuming typical sedimentary oolite granular structure. The wall rock dolomite is strongly silicified, and consists mainly of dolomite and quartz. The talc ore and dolomite show similar REE patterns, with low REE content, weakly negative Ce anomaly, and weak enrichment of HREE in relation to LREE. They also show similar Sr isotopic compositions, with 87Sr/86Sr ratios of 0.7092～0.7101 for both talc and dolomite. The dolomite has δ 13CV-PDB values of -4.9‰ to 0.7‰, similar to the range of the contemporaneous seawater. These data indicate that the magnesium in the talc ore and dolomite probably shared the same source and might have originated from the seawater. However, some of the samples also show positive Eu anomalies, lower δ 18Ov-SMow(14.5%o～19.7%o), and slightly higher 87Sr/86Sr values than the contemporaneous seawater values, and these characteristics may suggest an additional source besides seawater that contributed to the formation of talc ore. The authors hold that the required silicon in talc was probably provided by silica-rich hydrothermal fluid with slightly higher 87Sr/86Srvalues than the seawater. It is considered that the Yangcun talc deposit may have a syngenetic hydrothermal sedimentary origin. Magnesium was mainly derived from magnesium-rich seawater and silicon was mainly derived from silicon-rich and high 87Sr/86Sr hydrothermal fluid which was formed by seawater infiltrating and leaching of the old crustal strata. After synsedimentary deposition, talc ores also underwent strong metamorphism and deformation, which formed talc schist with typical schistosity structure.关键词
地质学/鲕粒滑石/稀土元素配分模式/C-O-Sr同位素/同生热水沉积/江西杨村Key words
geology, oolite granular talc, REE patterns, C-O-Sr isotope, syngenetic hydrothermal sedimentary origin, Yangcun, Jiangxi Province分类
天文与地球科学引用本文复制引用
雷焕玲,蒋少涌,孙岩,罗平,李艳红,马振兴..江西广丰杨村超大型滑石矿床成因探讨[J].矿床地质,2012,31(2):241-254,14.基金项目
本文得到国家重点基础研究973项目(编号:2012CB406706)资助 （编号:2012CB406706）
