Untested steam heated alteration cell with historic mercury production
Low-sulfidation epithermal mineralization along northwest trending structures below well-developed steam heated alunite-kaolinite-dickite alteration cell in historic mercury mining district.
The Polaris property is located 70km west of the town of Burns in Lake County, Oregon.
The area was known for mercury production as far back as 1933. Subsequent geothermal exploration was conducted by various groups beginning in the 1970s. The steam heated alteration cell itself is not prospective for hot water, as the geothermal cell appears to have migrated since the ~6Ma formation of acid sulfate alteration. In 1989, the property underwent a short gold exploration program by Galactic Resources, although the results and extent of the program remains unclear. Between 2008-2019, Ormat conducted geothermal exploration, which was partially funded by the Department of Energy. Exploration included multiple geophysical surveys, geologic mapping, a hyperspectral survey, and drilling of a 3000’ diamond core well. All the data from their exploration was made available as part of their DOE contract.
The Polaris project area is located along the eastern edge of the 6.49Ma Glass Buttes rhyolite dome complex. The complex occurs along a NW migrating chain of magmatism localized by the Brother’s Fault Zone, which is a regional and complex northwest trending en echelon fault system. Other low-sulfidation systems, such as Quartz Mountain, occur along similar structures to the south.
Silicic volcanism at Polaris is interfingered with basalt flows. These units have undergone steam heated alteration, apparently localized by WNW trending faults, which host strong opaline to chalcedonic silicification, as well as a majority of the mercury mineralization. Steam heated alteration is characterized by widespread alunite-kaolinite-dickite clay assemblages extending for at least 3km along the Antelope Ridge fault at the north end of the property, and for 2.5km along the southern Cascade Ridge fault. This system represents a largely untested steam heated alteration cell with strong structural controls.