Thermal and geochemical footprints of low-temperature sedimentary rock-hosted hydrothermal Au-systems: identifying far-field vectors toward ore

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New mineral occurrences at the earth's surface are rare. Future discoveries will depend on subsurface exploration and this requires the far-field detection of such ore deposits. Sedimentary rocks are important hosts for world-class deposits of Au, Pb, Zn & Cu in Canada and the world. They form at <4-6 km depth from the upwelling of hot fluids derived from hotter levels of the crust. Defining the far-field expression of these systems is challenging owing to their low temperature (<200-250 C) and subtle, spatially restricted and poorly constrained, alteration halos.This project uses an integrated set of analytical techniques to derive a model of the thermo-chemical expression of hydrothermal fluid flow in sedimentary rock-hosted Au-deposits. Specifically we will apply detailed and geologically constrained geochemistry, mineral alteration, and stable isotope studies (H, O & C), with low temperature thermochronology (apatite fission-track, apatite & zircon (U-Th)/He). The former techniques provide chemical information that tracks the passage of the mineralizing fluids through the rocks. The low-temperature thermochronology provides a means to track the thermal effect of the hydrothermal fluids as they pass through the rocks. Together, these two approaches will enable us to understand the spatial-thermal-chemical evolution of sedimentary rock-hosted systems in a way not previously possible.Having built such a model of the proximal to distal expression of such, we will develop a cost-effectivesampling and analysis strategy using the best combination of thermochronology, thermometry and geochemical/ mineralogical tracers to provide reliable far-field vectors toward ore.We will focus our study on Carlin-type sedimentary rock-hosted Au-deposits in Nevada; the third highestAu-producing area in the world.