Abstract Mineralization ages of many mineral deposit types (such as orogenic Au, stratabound Cu, and Mississippi Valley-type Pb-Zn deposits) are still difficult to date by the traditional isotopic chronometry because of the lack of suitable minerals. We have made efforts to establish a widely suitable dating technique to determine ore formation ages using a high-precision 40Ar/39Ar method on ubiquitously present fluid inclusions in quartz, sphalerite, and other nonpotassium minerals from hydrothermal deposits. The Xitian W-Sn polymetallic deposit in central South China contains several minerals suitable for isotopic dating for interchronometer comparison. 40Ar/39Ar laser step heating of 16 micas from ore veins, greisen, and metallogenic granites yields flat age spectra and thus well-defined ore formation ages ranging from 152.4 ± 1.5 (2σ) to 148.1 ± 1.4 Ma with an average of 150.2 ± 0.6 Ma. 40Ar/39Ar progressive crushing of nine quartz samples produces well-defined isochron lines for their primary fluid inclusions corresponding to isochron ages of 153.7–149.9 Ma with an average of 151.6 ± 0.6 Ma. Cassiterites from three hand specimens have weighted mean 206Pb/238U ages of 151.5 ± 1.7 (2σ), 149.7 ± 2.1, and 151.7 ± 2.1 Ma. All these new geochronological dates and previous molybdenite Re-Os ages yield well-constrained mineralization ages of 153–148 Ma for the Xitian W-Sn polymetallic deposit, which also confirms conclusively that the quartz 40Ar/39Ar progressive crushing technique is a feasible, valid dating technique. Furthermore, significant age information on the secondary fluid inclusions is potentially obtained simultaneously by this technique. We expect that this novel dating technique will be widely applied to determine the geologic fluids trapped in minerals during hydrothermal mineralization, hydrocarbon accumulation, metamorphism, tectonic activities, and other geologic processes.

中文翻译：

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华南西田钨锡多金属矿床 40Ar/39Ar 和 U-Pb 综合测年技术确定成矿年龄

摘要 许多矿床类型（如造山带Au、层系Cu、密西西比河谷型Pb-Zn矿床）的成矿年龄，由于缺乏合适的矿物，仍然难以用传统的同位素测年法进行测年。我们努力建立一种广泛适用的测年技术，使用高精度 40Ar/39Ar 方法对热液矿床中普遍存在的石英、闪锌矿和其他非钾矿物中的流体包裹体进行测定。华南中部的西田钨锡多金属矿床含有几种适合同位素测年的矿物，可用于年代际比对。40Ar/39Ar 激光阶梯加热来自矿脉、格雷森和成矿花岗岩的 16 个云母，产生平坦的年龄光谱，因此明确的成矿年龄范围为 152.4 ± 1。5 (2σ) 至 148.1 ± 1.4 Ma，平均为 150.2 ± 0.6 Ma。9 个石英样品的 40Ar/39Ar 渐进破碎为其主要流体包裹体产生了明确的等时线，对应的等时线年龄为 153.7-149.9 Ma，平均为 151.6 ± 0.6 Ma。三个手标本的锡石加权平均 206Pb/238U 年龄分别为 151.5 ± 1.7 (2σ)、149.7 ± 2.1 和 151.7 ± 2.1 Ma。所有这些新的地质年代学日期和以前的辉钼矿 Re-Os 年龄都为西田 W-Sn 多金属矿床产生了 153-148 Ma 的受约束的成矿年龄，这也最终证实了石英 40Ar/39Ar 渐进破碎技术是一种可行的、有效的约会技巧。此外，该技术可能同时获得有关次生流体包裹体的重要年龄信息。