Ore fluids in the porphyry copper deposit at Copper Canyon, Nevada

Economic Geology
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Abstract

The large, low-grade copper and gold deposit at Copper Canyon, Lander County, Nevada, formed in the contact metasomatic environment adjacent to a shallow Tertiary intrusion. Vein and disseminated chalcopyrite-pyrite-pyrrhotite-arsenopyrite mineralization, with lesser amounts of gold, galena, sphalerite, marcasite, and siderite occur in the Upper Cambrian Harmony and Middle Pennsylvanian Battle Formations. Studies of fluid inclusions in stages of vein quartz and in healed fractures through quartz phenocrysts and pebbles reveal the presence of very saline, sometimes CO 2 -rich fluids in the early and middle stages of mineralization. Ore fluid salinities during the base metal mineralization were approximately 40 wt percent, and temperatures were near 375 degrees C. Circulation of this hot brine was apparently restricted to an elongate highly fractured zone within 3,000 feet laterally of the intrusive. Later fluids in this central zone were somewhat cooler, near 300 degrees C, and had significantly lower salinities in the range 12 to 1.2 wt percent. Smaller lode deposits approximately 1 to 5 miles from the intrusion appear to have formed from low to moderate salinity fluids at temperatures generally in the range 250 to 335 degrees C. Geologic and fluid considerations suggest formation at approximately 6,000 feet in depth.

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Publication type Article
Publication Subtype Journal Article
Title Ore fluids in the porphyry copper deposit at Copper Canyon, Nevada
Series title Economic Geology
DOI 10.2113/gsecongeo.66.3.385
Volume 66
Issue 3
Publication Date May 01, 1971
Year Published 1971
Language English
Publisher Society of Economic Geologists
Description 15 p.
First page 385
Last page 399
Country United States
State Nevada
County Lander County
Other Geospatial Copper Canyon
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