Chemical fingerprinting and tracing of fluids in hydrothermal ore deposit systems

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A wide spectrum of hydrothermal ore-deposit settings (high-T magmatic to low-T diagenetic) are important for a wide variety of metals used to sustain the needs of our modern and continually evolving society. Exploration for resources depend to a large extent on successful mineral exploration, which itself relies on ore-deposit models at different scales; to be effect such models need constant refining. The latter results from the ongoing iteration of many observations which begin in the field and extend to the laboratory where extensive study and analyses occur using the most up-to-date analytical equipment. In addition, as hydrothermal ore deposits represent highly anomalous concentrations of metals, they reflect unusual processes in the Earth's crust. Thus improving our understanding ore-deposit phenomena also contributes to furthering our knowledge of Earth systems on different scales through time in regards to the lithosphere, hydrosphere and atmosphere. My research group uses an integrated field and geochemical approach for a number of ore deposit types (e.g., orogenic and intrusion-related Au,, porphyry (Cu-Au, Sn, rare metals), pegmatites (Li), low T sedimentary-rock hosted (Zn-Pb, Cu)). This approach relies in part on using the chemical signal preserved in both fluid inclusions (<10-50 um size fluid aliquots) hosted in minerals and also mineral phases themselves (e.g., pyrite, scheelite); both can be used as proxies for ore forming processes. The intent of the current proposal is to use the advances made by my research group and modern analytical technology, such as LA ICP-MS, to further explore our understanding of gold deposit settings. The approach used is a fluid-chemical one and relies on the recent advances in several instruments that provide the capability to analyse phases at the micron scale. For example, we can now acquire both the age of formation and geochemical signature for several single mineral phases relevant to ore systems, e.g., scheelite (W), tantalite (Ta, Nb), cassiterite (Sn). Scheeite is of particular importance to this study as it is a common phase in different gold systems which allows them to be contrasted. The project will address the application of the methodology in three graduate student projects specifically addressing issues related to better characterizing the fluids and mineral phases (e.g., scheelite, arsenopyrite) in gold systems in order to better discriminate gold deposit types, in particular the orogenic and intrusion-related clans. Data generated will be used to  further develop robust mineral deposit models for the latter gold deposit settings and better define the overall deposit genesis and thus Earth system processes at different scales. The three projects described below are discrete in their method, but overlap in intent and deposit types. Importantly, the methodology used can be transferred to other ore-deposit settings and thus has widespread application to ore systems in general.