Linking high spatial resolution accessory mineral chemistry and geochronology to large-scale ore-forming hydrothermal processes in the crust.

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The chemistry of fluids and conditions during the formation of hydrothermal ore deposits can be recorded by the composition of accessory minerals that crystallize with ore minerals. In order to evaluate accessory minerals as recorders of the processes and conditions under which ore deposits form, detailed mineral characterization, at a single crystal to deposit scale, is required through high resolution, in-situ, chemical analysis. The long-term goal of this research program is to develop new applications of mineral chemistry in order to resolve uncertainties regarding the processes and conditions which form ore deposits. The proposed research will examine the controls and variation of phosphate mineral chemistry, with a focus on apatite (the most common phosphate in the crust) in two hydrothermal settings: high temperature W skarn deposits of the Canadian Cordillera, and low temperature unconformity-type U deposits (UTUD) of the Athabasca Basin, Saskatchewan. The short-term objectives of this proposal are to elucidate the following uncertainties regarding phosphate minerals & these hydrothermal systems: i) evaluate how the composition & variability of phosphates (particularly the ore and associated metal content) can resolve the source of fluids & metals in hydrothermal ore systems such as W skarn & UTUDs, ii) resolve phosphate mineralogy, mineral chemistry & isotope systematics in distinct high T & low T reaction zones; iii) determine how coeval minerals impact partitioning of metals & other trace elements between fluid-phosphate, and iv) assess the effects of secondary hydrothermal events on the composition of phosphates in order to evaluate the retention of trace elements, & conditions in which phosphates are altered &/or destroyed. Five projects are proposed to address the above objectives. These projects will be completed by PhD, MSc and BSc level HQP trainees under the applicant's supervision. The chemistry of phosphates will be investigated at a variety of scales using microanalytical techniques including electron probe microanalyser, laser ablation inductively coupled plasma mass spectrometry, and secondary ion mass spectrometry. The results will be regularly communicated to the public through conference presentations by HQP, and peer-reviewed scientific articles. The proposed research activities are innovative & significant to geoscientists & industry, as it will reveal the controls, distribution, & implications of ore metals in phosphates in hydrothermal systems. This information will be linked with isotopic data allowing the application of phosphate minerals to be extended to infer metal & fluid sources in hydrothermal environments, & identify other processes in time that led to ore deposition. In the long term, the proposed research program will continue to develop new applications for spatially resolved accessory mineral chemistry in barren and mineralized hydrothermal systems.