| 广东大降坪黄铁矿矿床的铅、钕同位素及金属成矿物质来源探讨 |
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| 引用本文：.1998.Pb and Nd isotopes of the Dajiangping pyrite deposit, Guangdong Province, and its metallic ore source[J].Mineral Deposits,17(3):215~223 |
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| 基金项目:国家自然科学基金（49572114）和中国科学院九五重点B项目和国家九五攀登项目（KZ-952-S1-435） |
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| 中文摘要:大降坪黄铁矿矿床3号、4号矿体和硅质物的铅同位素指示，铅来源于基底混合岩和矿体围岩细碎屑岩的混合，灰岩的铅同位素反映是细碎屑岩或基底混合岩和震旦纪海水的混合铅。矿石和围岩207Pb／204Pb比值高，具有占老基底铅同位素组成特征。钕模式年龄与207Pb／204Pb显示出较好的正相关关系，说明具放射成因越高，铅来源于越老的地壳。块状矿石和硅质物的εNd= -13.9~ -16.5, 钕模式年龄tDM为1340×l06～2859×l0 l06a，反映其物源为占老的前震旦纪綦底物质。Sm-Nd等时线年龄为(230+ 13)×l0 l06 a，或许反映了粤西地区占特提斯构造运动的热动力事件年龄。 |
| 中文关键词:黄铁矿矿床，铅和钕同位素，金属成矿物质来源，广东大降坪 |
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| Pb and Nd isotopes of the Dajiangping pyrite deposit, Guangdong Province, and its metallic ore source |
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| Abstract:The authors have determined the isotopic com positions of Pb and Nd in ores and host rocks from Dajiangping pyrite deposit. The pyrite ores, single pyrite grains and cherts formed by hydrothermal sedimentation have similar Pb isotopic compositions and limited lead isotopic ratio ranges of 206Pb/204Pb 18.138~ 18.431, 207Pb/204Pb 15.622~15.871, and 208Pb/204Pb 38.299~ 39.041. These ratios are between the values of fine clastichost rocks and those of Yunkai P re-Sinain basement migmatites. This means that Pb was removed from the Yunkai Pre-Sinain basement migmatites and fine clastic host rocks by the hydrothermal water. The Pb isotopic compositions are distributed linearly in the 207Pb/204Pb versus 206Pb/204Pb and 208Pb/204Pb versus 206Pb/204Pb diagrams, with high 207Pb/204Pb ratios that characterize Gondwana basement. The 207Pb/204Pb ratios of cherts and pyrite ores from N0.4 massive ore-body are positively correlated w ith tNdDM (0), implying that the Pb is m ore radiogenic and is derived from older crust materials. The Pb isotopic compositions of limestones are distributed linearly but with different slopes in the 207Pb/204Pb versus 206Pb/204Pb and 208Pb/204Pb versus 206Pb/204Pb diagrams and are between the values of fine clastichost rocks or Yunkai basement migmatites and those of Mn nodules, suggesting that Pb was their mixture. The tDM and εNd(0) of the massive ore and chert are 1340×l06~ 2859×l06 a and -13.9~ -16.5 respectively. This means that the Nd was derived from the Pre-Sinian basement, which is consistent with the Pb isotopic results. The isochron age of ( 230+13)×l06 a may indicate a tectonic hydrothermal event of the Indo-Chinese epoch. |
| keywords:pyrite deposit, Pb and Nd isotope, metallic ore, Dajiangping in Guangdong |
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