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Western Region Gold Deposits

WESTERN REGION GOLD DEPOSITS PROJECT, RFO ACTIVITIES:

The Western Region Gold Project involves more than twenty USGS scientists who are conducting research on gold deposits and their geologic settings in northern Nevada. In the Reno Field Office, Steve Peters and Alan Wallace are studying various aspects of sedimentary rock-hosted (Carlin-type) gold deposits and volcanic-hosted epithermal gold-silver-mercury deposits.  A recent summary of work can be found at http://geopubs.wr.usgs.gov/open-file/of98-338/

Tertiary volcanic rocks and epithermal mineral deposits

Mapping by Alan Wallace in the Ivanhoe mining district and the Snowstorm Mountains in northern Nevada has focused on the relationship of late Tertiary volcanism and structure to the formation of epithermal gold, silver, and mercury deposits in the volcanic rocks of those areas.  Collaborative studies with David John (USGS, Menlo Park, CA) have focused on the northern Nevada rift, a narrow zone of Miocene volcanic rocks and faults that extends southeastward from the Oregon-Nevada border to east-central Nevada. The rift contains abundant middle Miocene volcanic rocks, and it is the site of several epithermal deposits, including Midas, Ivanhoe, Mule Canyon, Fire Creek, and Buckhorn. The new results show that the rift and the mineral deposits are related genetically and formed in the narrow time frame of about 16 to 15 Ma. Ongoing work includes mapping the geology of the Ivanhoe district and collaboration on the new, world-class Ken Snyder gold-silver deposit at Midas.

Sedimentary rock-hosted gold deposits

Mapping by Steve Peters has been conducted in the Carlin trend and in the Independence Mountains. Detailed work in the Betze gold deposit, Goldstrike Mine, along the Carlin trend, has documented structural controls of different ore types in this large ore body. Mapping in the Lynn window, south of the Carlin Mine, has focused on the orientation of folds, thrusts, and shear zones and their relation to the ore bodies. Mapping in the Bobs Flat quadrangle has centered on the lithologic and structural nature of the upper-plate rocks to the Roberts Mountain thrust and their deformation by the Crescent Valley-Independence lineament (CVIL). This lineament appears to have been active and acted as a fluid conduit before, during, and after gold events in the Independence, Carlin trend, and Cortez-Pipeline districts. Mapping in the Water Pipe Canyon and Mahala Creek West quadrangles in the Independence Range is focusing on individual strands of the CVIL and their relation to lithology, thrusts, folds, and gold ore bodies in the upper and lower plates of the Roberts Mountain thrust.

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Other Western Region Mineral Resources offices

Menlo Park / Spokane / Tucson

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