INTEGRATING STABLE ISOTOPE ANALYSIS WITH MINERAL EXPLORATION TO IMAGE HYDROTHERMAL SYSTEMS: APPROACHES, CHALLENGES, AND RESULTS

Mineral exploration programs can yield unparalleled access to fossil hydrothermal systems, but the pace and scale of these activities pose challenges for conventional approaches to documenting fluid-rock interactions. We have paired conventional carbonate mineral acidification preparations with new approaches in cavity-enhanced laser absorption spectrometry to allow for rapid analysis of carbonate mineral 13C and 18O contents in sulfide-mineral rich samples at a scale commensurate with mineral exploration programs. This allows imaging of large-scale hydrothermal systems in unprecedented detail and provides useful context for mineral exploration activities, but also presents challenges in data analysis and interpretation. In carbonate replacement and Carlin-style sediment-hosted deposits, km-scale 18O haloes surrounding mineralization centres provide vectoring opportunities in exploration and delineate structural and stratigraphic controls on fluid flow. Detailed interpretations, including quantification of fluid flow amounts, can be complicated by kinetic processes as well as complex and overlapping fluid flow systems. When coupled with paragenetic alteration studies, individual fluid flow systems can be identified. Paired analysis of wall rocks and hydrothermal vein sets allow the competing influences of hydrodynamic and kinetic dispersion to be evaluated. Dimensionless approaches to interpreting vein-wallrock pair data may yield insights in sample suites that lack clear spatial delineation with respect to fluid inlets, a common problem in large exploration datasets.