The source of fluids associated with critical-mineral formation in the Mulgrave Lake, Barrington, Shelburne, and Port Mouton plutons, Nova Scotia

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The goal of the proposed research is to provide an understanding of the processes required to form critical element deposits in Nova Scotia. To achieve our goal, we plan to: (1) develop an inventory and paragenesis for the critical minerals in the plutons south and east of the main body of the South Mountain Batholith; (2) analyze the H and O isotopic composition of the micas/feldspars that are associated with or host critical elements such as Nb and Li, using our in situ SIMS technique to determine the source of the fluid (magmatic vs. hydrothermal); (3) date these micas/feldspars using Ar-Ar to determine the timing of these fluids; and (4) analyze the bulk rare earth elements (REE) contents of these intrusive rocks to determine if they have unique REE patterns that can be used as an exploration tool.Our research will focus on the Nb-rich Mulgrave Lake pluton and the Be-Mo-rich Port Mouton, Shelburne, and Barrington Passage plutons and associated pegmatites. The Nova Scotia Geological Survey (NSGS) will use these data to ultimately refine the geological and geochemical models for critical element deposits in Nova Scotia. Data interpretation and presentation include statistical analyses that incorporate both spatial and temporal relations of the mineralogical and geochemical data, identification of key processes that resulted in ore formation, and estimates of the duration of fluid events required to generate critical element ores. This work will significantly contribute to our knowledge of igneous systems that host these deposits, and in particular the processes that transport, concentrate, and modify critical elements. The proposed research will train 1 MSc student and 1 undergraduate student in critical element ore deposits. Geologists from the NSGS will contribute to the training of these students in field work techniques.