Ore Precipitation in Epithermal Systems

建议对俄勒冈州卡斯卡德西部波西米亚地区Champion矿的浅成热液矿床进行实地和实验室联合研究。该矿床脉体记录了多期流体流动和沉淀。一名参与该项目的博士生绘制了领域关系图。他们将详细研究（流体包裹体测量，矿石、脉石和蚀变矿物的显微探针分析，火成岩和矿化期的Ar-Ar年代学）。观测数据将根据成矿理论模型进行解释，包括成矿盐水的冷却、沸腾、混合和氧化还原历史。数值模拟将用于模拟(a)硫化物和金沉淀的机制，以及(b)与围岩之间的传热作用。这些研究对认识许多浅成低温热液矿床具有一定的应用价值。

A combined field and laboratory study is proposed for epithermal ore deposits of the Champion Mine, Bohemia district, in the western Cascades, Oregon. Veins in this deposit record multiple episodes of fluid flow and precipitation. Field relations have been mapped by a PhD student involved in the project. They will be studied in detail (fluid inclusion measurements, microprobe analysis of ore, gangue, and alteration minerals, and Ar-Ar geochronology of igneous and mineralization episodes). Observational data will be interpreted in terms of theoretical models of ore formation involving cooling, boiling, mixing, and redox histories of ore forming brines. Numerical simulations will be used to model (a) mechanisms of sulfide and gold precipitation, and (b) the role of heat transfer to and from wall rocks. These studies will be of application to understanding many epithermal ore deposits.