| 豫西熊耳山寨凹钼矿床辉钼矿铼-锇年龄及其地质意义 |
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| 引用本文：LI HouMin，YE HuiShou，WANG DengHong,CHEN YuChuan,QU WenJun and DU AnDao.2009.Re-Os dating of molybdenites from Zhaiwa Mo deposit in Xiong’er Mountain, western Henan Province, and its geological significance[J].Mineral Deposits,28(2):133~142 |
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| 基金项目:自然科学基金项目“滇东北峨眉山玄武岩铜矿中有机质对铜富集成矿的作用”（编号40572060）、地质大调查项目《我国西部重要成矿区带矿产资源潜力评估》（编号1212010535804）、《中国成矿体系综合研究》（编号1212010634002）和《我国重要矿产和区域成矿规律研究》（编号1212010633903） |
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| 中文摘要:寨凹钼矿床位于河南熊耳山地区，是新近发现的穿插于太古宙太华岩群深变质岩中的辉钼矿石英脉型钼矿床。为了获得该钼矿床的成矿年龄，从10件采自辉钼矿石英脉的样品中挑选出辉钼矿单矿物进行Re-Os同位素年龄测定。10件辉钼矿样品22次测定结果的年龄最小值为（1 680±24）Ma，最大值为（1 831±29）Ma。其中10件辉钼矿粗粒（自然粒度）状态下13次测定结果的等时线年龄为（1 686±67）Ma，MSWD=16；4件研磨后粉末状辉钼矿9次测定结果的等时线年龄为（1 804±12）Ma，MSWD=1.09。两条等时线的初始187Os值在误差范围内接近于0，表明187Os全部由Re衰变而来。上述结果表明，寨凹钼矿床形成于17~18亿年的中元古代早期，是目前中国已知最老的钼矿床，为中元古代早期华北克拉通伸展 裂解环境中构造 岩浆热事件所伴随的热液成矿作用的产物，与熊耳群火山岩浆活动有密切的时空和成因联系；辉钼矿的Re含量为4.832×10-6~0.665×10-6，平均3.045×10-6，表明成矿物质可能来自围岩地层。东秦岭地区从元古宙到印支期、燕山期的钼矿化构成该区的钼成矿谱系，寨凹钼矿床可能是该谱系中最早的端员。 |
| 中文关键词:地球化学 Re-Os同位素定年 辉钼矿 钼矿床 成矿谱系 寨凹 豫西 |
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| Re-Os dating of molybdenites from Zhaiwa Mo deposit in Xiong’er Mountain, western Henan Province, and its geological significance |
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| Abstract:The Zhaiwa Mo deposit in the Xiong’er Mountain of western Henan Province is a quartz vein type molybdenite deposit newly discovered in the hypometamorphic rocks of Archean Taihua Group. In order to determine the age of the deposit, the authors selected pure molybdenite grains from 10 quartz molybdenite vein type ore samples for Re-Os isotopic dating. The Re-Os ages obtained from 22 analyses of 10 molybdenite separates range from (1 680±24) Ma to (1 831±15) Ma. The 13 data of the above 22 analyses of 10 molybdenite separates in natural coarse grains give a 187Re-187Os isochron of (1 686±67) Ma with MSWD being 16. The 9 data of the above 22 analyses of 4 molybdenite separates in milled powder state give a 187Re-187Os isochron of (1 804±12) Ma with MSWD being 1.09. The original 187Os values of both 187Re-187Os isochrons approach zero within the reasonable error extent, suggesting that all the 187Os resulted from the decay of Re. All this suggests that the ore forming process of the Zhaiwa Mo deposit occurred in an extension broken setting of North China Craton at the late stage of Paleoproterozoic and hence the deposit might be the oldest Mo deposit in China. The Re content of the molybdenite ranges from 4.832×10-6 to 0.665×10-6 with an average value of 3.045×10-6, implying that the metallogenetic materials were leached from host rocks. Intermediate basic dykes are associated with volcanic rocks of Paleoproterozoic Xiong'er Group, implying that Mo mineralization was related to the Paleoproterozoic magmatim. Mo mineralization in East Qinling Mountains took place from Middle Proterozoic through Indosinian to Yanshanian and constituted a Mo metallogenetic sequence, with the Zhaiwa Mo deposit being the oldest end member of this sequence. |
| keywords:geochemistry, Re-Os dating, molybdenite, Mo deposit, metallogenetic sequence, Zhaiwa, western Henan Province |
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