MINERALIZATION IN AURORA, NV AND BODIE, CA OBSERVED WITH AEROSPACE GEOPHYSICAL DATA

The Aurora and Bodie mining districts are located in the Miocene volcanics of the Bodie Hills, north of Mono Lake, on the opposite sides of Nevada-California state line. From the standpoint of economic geology, both deposits are structurally controlled, low-sulfidation, adularia-sericite precious metal vein deposits with an extensive alteration halo. The area has been exploited since late 1870's by both underground and minor open pit operations (Aurora), exposing portions of altered andesites, devitrified rhyolites and quartz-adularia-sericite veins. Much of the geologic mapping and explanation was ad-hoc and primarily in support of the mining operations, without particular interest paid to the system as a whole. A combined array of geophysical data in conjunction with traditional field mapping can be utilized to attain better understanding of the districts in both local and regional framework. The potential fields data (gravity, magnetic field) suggest a presence of an intrusive mass at depth in Bodie Hills as well as numerous structural features (faults). Multispectral, spaceborne imagery (Landsat ETM, ASTER) shows the regional setting and limited information on the lithology, alteration and structural framework of the Bodie Hills. The high-resolution, narrow-swath, hyperspectral data-sets, including the high and low altitude AVIRIS, MASTER and SEBASS (Spatially Enhanced Broadband Area-array Spectrograph System), targeted on the individual districts, allows identification of hydrothermal alteration assemblages, potential structural mineralization conduits and surface manifestations of mineralization. Individual segments of the regional-to-local geophysical survey are field checked and integrated in a GIS-driven and organized model. The model suggests a close relationship between the mineralization in Bodie Hills and regional structural and tectonic events shaping the western Great Basin