Geochronology of the Sleeper deposit, Humboldt County, Nevada: Epithermal gold-silver mineralization following emplacement of a silicic flow-dome complex

Economic Geology
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Abstract

The high-grade gold-silver deposits at the Sleeper mine are low sulfidation, quartz-adularia-type epithermal deposits, formed during the final stages of igneous hydrothermal activity of a small middle Miocene silicic flow-dome complex in north-central Nevada. Potassiumargon and 40 Ar/ 39 Ar ages of alkali feldspar indicate that the rhyolitic flow-dome complex was emplaced before about 16.5 Ma; hydrothermal alteration and mineralization followed, lasting from about 16.2 to 14+ Ma based on ages of adularia associated with electrum. There were multiple pulses of alteration and mineralization but all occurred within a period of less than 2 m.y. Later supergene alteration formed opal and alunite about 5.4 Ma but produced no Au or Ag mineralization other than some remobilization to produce locally rich pockets of secondary Au and Ag enrichment and is unrelated to the older magmatic hydrothermal system. The Sleeper deposit in the northern part of the Great Basin is genetically related to bimodal volcanism that followed a long period of arc-related andesitic volcanism in the same general region.

Publication type Article
Publication Subtype Journal Article
Title Geochronology of the Sleeper deposit, Humboldt County, Nevada: Epithermal gold-silver mineralization following emplacement of a silicic flow-dome complex
Series title Economic Geology
DOI 10.2113/gsecongeo.88.2.317
Volume 88
Issue 2
Year Published 1993
Language English
Publisher Society of Economic Geologists
Description 11 p.
First page 317
Last page 327
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