Zoning and Age of Micron Gold Deposits

这里提出的研究涉及沉积物托管微米 金（SHMG）矿床，这是最大的化石热液 大盆地（图1）和最重要的 该项目将重点关注美国的黄金来源。 确定： 1)矿床规模分区，可提供以下信息： SHMG成矿流体的来源，以及 温度、压力和地壳深度 形成了 2)这些沉积物的年龄，这将澄清它们的 与岩浆热和水的关系， 大盆地的演变 大部分研究将在新发现的 后SHMG存款，延伸到深度超过2500英尺。和 含有大量的矿石， 风化和氧化。 分区研究将包括 矿物学、流体包裹体和稳定同位素测量。 放射性年龄测量将使用一个实验性的疏散 石英管/全脱气40 Ar-39 Ar法分析小于1 mg 蚀变矿物分离，这些年龄将被检查， 常规的~（40）Ar-~（39）Ar年龄测定方法， 矿石前和矿石后岩脉中的蚀变矿物， 后矿化。 我们的研究结果可以得出一个深度分区 SHMG矿床的分类，可用于 勘探和区域构造研究。

The research proposed here concerns sediment-hosted micron gold (SHMG) deposits, which are the largest fossil hydrothermal systems in the Great Basin (Fig. 1) and the most important sources of gold in the U.S. The project will focus on determination of: 1) deposit-scale zoning, which could provide information on the source of SHMG mineralizing fluids, as well as the temperature, pressure and crustal depth at which they formed. 2) the age of these deposits, which will clarify their relation to both magmatic heat and water, and the tectonic evolution of the Great Basin. Most of the study will be carried out on the newly discovered Post SHMG deposit, which extends to depths of over 2500 ft. and contains large volumes of ore that have not been overprinted by weathering and oxidation. Zoning studies will include mineralogical, fluid inclusion and stable isotopic measurements. Radiometric age measurements will use an experimental evacuated quartz tube/total degassing 40Ar-39Ar method to analyse less 1 mg of alteration mineral separates and these ages will be checked by conventional 40Ar-39Ar age determinations on igneous and alteration minerals in pre- and post-ore dikes, which bracket mineralization at Post. Our results could yield a depth-zoning classification for SHMG deposits, which could be used both in exploration and in regional tectonic studies.