STRUCTURAL CONTROLS ON MINERALIZATION AND FAULT REACTIVATION AT MARIGOLD MINE, HUMBOLDT COUNTY, NEVADA

Mineralization in the Battle Mountain mining district is strongly influenced by multiple deformation events including the Cenozoic Basin and Range extensional deformation that overprints Paleozoic and Mesozoic compressional structures. The younger deformation events potentially reactivated many older faults while preparing for gold mineralization in the district. This study focuses on sub-parallel N-S mineralized faults in the Terry Complex open pit at Marigold Mine, a gold mine located on the north end of the Battle Mountain mining district in Humboldt County, Nevada. Marigold’s disseminated mineralization is controlled by favorable sedimentary beds and near-vertical faults which constitute pathways for hydrothermal fluid transportation within the footwall of the Golconda Thrust. The gold is found dominantly in fault gouge and fractures within the quartzite beds of the Ordovician Valmy Formation and disseminated within the Pennsylvanian to Permian Antler group adjacent to the steeply dipping faults. By collecting kinematic indicators this study finds some of these mineralized faults have dip-slip movement overprinted by strike-slip movement.To better understand the orientation and movement and reactivation of the mineralized ‘feeder-faults’, this study presents a geologic map and 3D geological model with interpretation of structural and lithological features investigated in the Terry Complex open pit. Structural data were collected throughout the Terry Complex, with a focus on two traverses along sub-perpendicular highwalls near a N-S mineralized reactivated fault zone. Kinematic indicator measurements show initial normal movement of the faults before or during the Eocene(?) mineralization events with subsequent reactivation post-mineralization (likely Miocene or younger) as left lateral strike-slip. This study locally constrains the stress orientation of the reactivated faults in the Terry Complex with potential correlations with district and/or regional orientations.