Abstract Accurate and precise geochronology using the Re-Os isotopic system in pyrite is an invaluable tool for developing and confirming genetic models of ore systems. However, as a bulk method, the results produced by pyrite Re-Os geochronology are commonly complex, and many imprecise isochrons exist in the literature. Using LA-ICPMS methods it is now possible to map and quantify Re distribution at the ppb level, allowing an unprecedented look into the Re-Os systematics of pyrite-bearing ore. Two samples from the Lisheen Zn-Pb ore deposit in Ireland showing disparate Re-Os isotopic behavior were investigated. In-situ sulfur isotope measurements using SIMS, an analytical technique not previously attempted on the Irish deposits, was used to supplement the Re-Os dataset. A massive pyrite sample from the Main Zone produced a precise, low-scatter isochron (346.6 ± 3.0 Ma, MSWD = 1.6). The Re distribution in this sample is relatively homogeneous, with the Re budget dominated by pyrite containing 1–5 ppb Re, but the δ34S varies significantly from −45.2‰ to 8.2‰. A second, more paragenetically complex, sample from the Derryville Zone produced a younger age with high scatter (322 ± 11 Ma, MSWD = 206) and this also displays a large variation in δ34S (−53‰ to +4‰). The cores of grains of main-stage iron sulfide are depleted in trace elements and show low Re abundances ( A second Re-Os dataset from Zn-Pb mineralization at Hawker Creek, Nunavut, Canada was produced from massive pyrite that displays low Re concentrations ( In general, therefore, the complexities of pyrite Re-Os geochronology can result from impurities in mineral separates. Attempts to eliminate impurities through different mineral separation techniques (e.g. crushing, heavy liquid separation, magnetic separation, acid leaching) are frequently only partially successful and therefore full characterization of any resulting mineral separates is extremely important. We conclude that LA-ICPMS mapping of Re and Mo distributions is essential for the identification of such impurities. Although other trace element LA-ICPMS maps, in-situ sulfur isotope measurements, and petrographic evidence were of limited use in assessing the Re budget of a sample, they are invaluable in linking the documented Re distribution obtained through LA-ICPMS to Re-Os geochronological results.

中文翻译：

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了解 Re 在黄铁矿中的微尺度空间分布和矿物学驻留：来自碳酸盐岩 Zn-Pb 矿石的示例以及对黄铁矿 Re-Os 年代学的影响

摘要 在黄铁矿中使用 Re-Os 同位素系统进行准确和精确的年代学是开发和确认矿石系统成因模型的宝贵工具。然而，作为一种整体方法，黄铁矿 Re-Os 年代学产生的结果通常很复杂，并且文献中存在许多不精确的等时线。使用 LA-ICPMS 方法，现在可以绘制和量化 ppb 级的 Re 分布，从而对含黄铁矿的 Re-Os 系统进行前所未有的研究。研究了来自爱尔兰 Lisheen Zn-Pb 矿床的两个样品，显示出不同的 Re-Os 同位素行为。使用 SIMS 进行原位硫同位素测量，这是一种以前未在爱尔兰矿床上尝试过的分析技术，用于补充 Re-Os 数据集。来自主区的大量黄铁矿样本产生了精确的，低散射等时线（346.6 ± 3.0 Ma，MSWD = 1.6）。该样品中的 Re 分布相对均匀，Re 预算以含 1-5 ppb Re 的黄铁矿为主，但 δ34S 在 -45.2‰ 到 8.2‰ 之间变化很大。来自 Derryville 区的第二个更复杂的共生样本产生了更年轻的高散射（322 ± 11 Ma，MSWD = 206），这也显示了 δ34S（-53‰ 到 +4‰）的很大变化。主阶段硫化铁颗粒的核心缺乏微量元素并显示低 Re 丰度（来自加拿大努纳武特霍克溪的 Zn-Pb 矿化的第二个 Re-Os 数据集是由显示低 Re 浓度的块状黄铁矿产生的（因此，一般而言，黄铁矿 Re-Os 年代学的复杂性可能是由矿物分离物中的杂质引起的。通过不同的矿物分离技术（例如压碎、重液分离、磁选、酸浸）去除杂质的尝试通常只取得部分成功，因此对任何产生的矿物分离物进行全面表征非常重要。我们得出的结论是，Re 和 Mo 分布的 LA-ICPMS 映射对于识别此类杂质至关重要。尽管其他痕量元素 LA-ICPMS 地图、原位硫同位素测量和岩相证据在评估样品的 Re 预算方面用途有限，但它们在将通过 LA-ICPMS 获得的记录 Re 分布与 Re-O 联系起来方面非常宝贵地质年代学结果。酸浸出）通常只是部分成功，因此对任何由此产生的矿物分离物进行全面表征非常重要。我们得出的结论是，Re 和 Mo 分布的 LA-ICPMS 映射对于识别此类杂质至关重要。尽管其他痕量元素 LA-ICPMS 地图、原位硫同位素测量和岩相证据在评估样品的 Re 预算方面用途有限，但它们在将通过 LA-ICPMS 获得的记录 Re 分布与 Re-O 联系起来方面非常宝贵地质年代学结果。酸浸出）通常只是部分成功，因此对任何由此产生的矿物分离物进行全面表征非常重要。我们得出的结论是，Re 和 Mo 分布的 LA-ICPMS 映射对于识别此类杂质至关重要。尽管其他痕量元素 LA-ICPMS 地图、原位硫同位素测量和岩相证据在评估样品的 Re 预算方面用途有限，但它们在将通过 LA-ICPMS 获得的记录 Re 分布与 Re-O 联系起来方面非常宝贵地质年代学结果。