金顶超大型铅锌矿床的成矿金属来源——来自铅同位素组成的制约

发布时间：2018-02-04 16:33

本文关键词： 地球化学铅同位素金属来源测试误差金顶　出处：《矿床地质》2017年02期 　论文类型：期刊论文

【摘要】：金顶矿床是世界著名的超大型铅锌矿床,其巨量的金属堆积引起许多学者对成矿金属来源的关注。前人通过铅同位素示踪研究,提出了成矿金属来自地幔、上地壳、下地壳及不同端员混合等不同认识。理论分析表明,这些观点认识的差异可能源于不同作者分析铅同位素数据存在测试误差。基于此,笔者在金顶矿床选择了7个代表性硫化物样品,再次进行了铅同位素分析。结果显示,矿床铅同位素组成为~(206)Pb/~(204)Pb=18.3945~18.4429、~(207)Pb/~(204)Pb=15.6412~15.6583、~(208)Pb/~(204)Pb=38.6266~38.6772,在铅同位素演化模式图解(Zartman et al.,1979)中数据点分布集中,处于"造山带"和"上地壳"演化曲线之间,未显示出明显的线性分布特点,表明金顶矿床成矿金属来源主要为壳源;区域对比表明,金顶矿床明显比白秧坪矿带铅锌矿床贫放射性成因铅,而与区域VMS型矿床铅同位素组成更为接近,这表明金顶矿床与白秧坪矿带矿床有着不同的金属物源区,其金属可能来自盆地底部晚三叠世火山岩或其内早期的VMS矿化。
[Abstract]:The Jinding deposit is a world-famous superlarge lead-zinc deposit, and its huge amount of metal accumulation has aroused many scholars' attention to the source of metallogenic metals. Through the study of lead isotope tracer, it is suggested that the metallogenic metals come from the mantle. The theoretical analysis shows that the differences in these views may be due to the existence of testing errors in the analysis of lead isotopic data by different authors. Seven representative sulphide samples were selected from the Jinding deposit, and lead isotopic analysis was carried out again. The Pb isotopic composition of the deposit is Pb-P / R 204B ~ (b) ~ (18.3945) ~ 18.4429. A total of 207Pb / L / 204B / T 15.6412 / 15.6583 / 208B / L / 204PbN 38.6266n 38.6772. In the diagram of lead isotope evolution model Zartman et al. (1979), the distribution of data points is concentrated and lies between the "orogenic belt" and the "upper crust" evolution curve. There is no obvious linear distribution, which indicates that the ore-forming metal source of Jinding deposit is mainly crust source. The regional comparison shows that the Jinding deposit is much less radioactive than the lead-zinc deposit in the Baiyangping ore belt, and is closer to the lead isotopic composition of the regional VMS deposit. This indicates that the Jinding deposit has different metal source from the Baiyangping ore belt, and its metals may come from the late Triassic volcanic rocks at the bottom of the basin or the early VMS mineralization within the deposit.
【作者单位】：中国地质科学院地质研究所;中国地质大学地球科学与资源学院;烟台黄金职业学院;
【基金】：国家重点研发计划项目(编号:2016YFC0600306) 国家自然科学基金(编号:41273050;41403043;41320104004) 国土资源大调查项目(编号:DD20160024-02)联合资助
【分类号】：P618.4
【正文快照】： 3烟台黄金职业学院,山东招远265401)铅同位素是示踪矿床成矿物质来源的重要手段。然而,由于204Pb丰度低,质谱分析过程中会产生分馏和死时间效应;某些样品中铅含量低、铅同位素信号强度弱,导致许多地质样品难以获得可信的分析数据,铅同位素示踪的效果往往不佳。近年来,随着分析

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