The behaviour of metals in magmatic-hydrothermal systems

了解金属在岩浆-热液系统中的行为是破译多种类型矿床成因的关键。由于激光烧蚀诱导等离子体质谱(LA-ICPMS)分析矿物、流体包裹体和熔体包裹体中的金属的发展，这一认识在过去几年中有了显著的提高。这项研究将利用这项技术研究稀有金属(Ta-Nb-Sn-W-Mo)和贵金属(Pt-Pd-Au)矿床。随着电子产品和特种合金的新用途不断开发，稀有金属的重要性越来越大，而且由于价格居高不下，人们对贵金属的兴趣依然浓厚。为了改进勘探模式，有必要更好地了解集中这些元素的过程。这将通过实地调查来完成，其中矿石金属的丰度将在流体和熔体包裹体中确定。根据这些数据，将评估岩浆作用与热液作用的相对重要性。实地研究还将检查特征元素是否集中在关键矿物中。这些指示矿物与成矿作用之间的时空关系将被刻画出来，并应用于建立矿床成因模式，以及评价指示矿物在热液矿床勘查中的应用。还将进行补充的实验研究。其中包括测定Ta的扩散系数和Ta矿物在花岗岩熔体中的溶解度，以及利用合成流体包裹体研究元素在不混溶流体的汽相和液态之间的分配，特别是Au-As-Sb-Mo-W。

Understanding the behaviour of metals in magmatic-hydrothermal systems is the key to deciphering the origin of many types of ore deposits. This understanding has improved dramatically in the last few years because of the development of laser ablation induced couple plasma mass spectrometry (LA-ICP-MS) analyses of metals in minerals, fluid inclusions and melts inclusions. The proposed research will take advantage of this technique to study 'rare-metal' (Ta-Nb-Sn-W-Mo) and precious metal (Pt-Pd-Au) ore deposits. The rare-metals are increasingly more important as new uses in electronics and specialty alloys are developed, and because of high prices, the interest in precious metals continues to be strong. It is necessary to better understand of the processes that concentrate these elements in order to improve exploration models. This will be accomplished by field investigations, where the abundances of the ore metals will be determined in fluid and melt inclusions. From these data the relative importance of magmatic versus hydrothermal processes will be evaluated. The field studies will also examine whether characteristic elements are concentrated in key minerals. The spatial and temporal relationships between these indicator minerals and mineralization will be characterized and applied to generating genetic models of ore deposits, and evaluating the use of indicator minerals to exploration of hydrothermal ore deposits. Complementary experimental studies will also be conducted. These include determining the diffusivity of Ta and solubility of tantalum minerals in granitic melts, and the use of synthetic fluid inclusions to study element partitioning, notably Au-As-Sb-Mo-W, between vapour and liquid phases of immiscible fluids.