【摘要】 石英是热液矿床的常见矿物,分布广泛。石英流体包裹体⁴⁰Ar/³⁹Ar定年技术为解决矿床年龄测定难题开辟了新的途径,但以前的研究工作缺少共生钾矿物年龄对比验证。本文选择柿竹园多金属矿床共生白云母和石英进行⁴⁰Ar/³⁹Ar测年分析对比研究。白云母激光阶段加热坪年龄为（153.7±0.9）Ma,代表了成矿年龄。采用真空击碎技术提取石英流体包裹体进行⁴⁰Ar/³⁹Ar年龄测定,获得了逐渐下降型年龄谱,在反等时线图上数据点构成高度线性相关的等时线,年龄为（152.3±5.7）Ma,代表了原生包裹体的年龄。石英原生流体包裹体等时线年龄与共生白云母年龄一致,表明石英流体包裹体⁴⁰Ar/³⁹Ar技术是行之有效的矿床定年方法。此外,K-Cl-40Ar图解可以区分石英中的原生、次生包裹体,并获得次生包裹体年龄为¹00 Ma,与矿区钾长石脉年龄一致,指示了一次后期热液活动的时间。更多还原

【Abstract】 Quartz is a common mineral in hydrothermal deposits. ⁴⁰Ar/³⁹Ar dating technique for fluid inclusions in quartz by crushing in vacuo provides a new approach to dating mineralization of hydrothermal deposits. However, rare K-rich minerals are available for ⁴⁰Ar/³⁹Ar dating to confirm the validity of this new technique in previous studies. In this study the authors selected paragenetic quartz and muscovite in a piece of ore collected from the Shizhuyuan polymetallic deposit for ⁴⁰Ar/³⁹Ar dating. For the muscovite sample laser stepwise heating results in a very flat age spectrum with a plateau age of（153.7±0.9） Ma（1σ）. For the quartz sample crushing in vacuo yields an age spectrum marked with abnormal old apparent ages, which declines step-by-step for the first ten steps（steps 1 – 10）, and is followed by a plateau for the last ten steps（steps 11²0）. The data points for steps 11²0 constrain a well-defined isochron corresponding to an age of（152.3±5.7） Ma with an initial 40Ar/36 Ar value of 291.7, which can be interpreted as the contributions from the primary fluid inclusions without excess 40 Ar inside. The isochron age for the primary fluid inclusions in quartz is well concordant with that of paragenetic muscovite, indicating that the quartz ⁴⁰Ar/³⁹Ar stepwise crushing technique is an effective method for obtaining ages of primary fluid inclusions in hydrothermal deposits. In addition, the primary and secondary fluid inclusions could be distinguished into two groups by plots based on correlations among the ratios of K, Cl and Ar. The ages of secondary fluid inclusions are obtained from these plots（¹00 Ma）, which are concordant with the ⁴⁰Ar/³⁹Ar plateau age of the K-feldspar vein, suggesting a post-hydrothermal activity in formation of the ore deposit.更多还原