Dike-hosted ores of the Beast Deposit and the importance of Eocene magmatic in gold mineralization of the Carlin Trend, Nevada

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doi: 10.2113/gsecongeo.95.7.1417
Authors:Ressel, Michael W.; Noble, Donald C.; Henry, Christopher D.; Trudel, Wayne S.
Author Affiliations:Primary:
University of Nevada, Mackay School of Mines, Department of Geological Sciences, Reno, NV, United States
Other:
Nevada Bureau of Mines and Geology, United States
Newmont Gold Company, United States
Volume Title:Economic Geology and the Bulletin of the Society of Economic Geologists
Source:Economic Geology and the Bulletin of the Society of Economic Geologists, 95(7), p.1417-1444. Publisher: Economic Geology Publishing Company, Lancaster, PA, United States. ISSN: 0361-0128
Publication Date:2000
Note:In English. 85 refs.; illus., incl. sect., 3 tables, geol. sketch maps
Summary:The Beast, a low-grade (7.3 m.y. at 0.7 g/t), disseminated Au deposit in the Carlin Trend, Nevada, is unique among Carlin-type Au deposits in having as much as 50% of the ore hosted by a 37.3 m.y. porphyritic rhyolite dyke. Nonetheless, the deposit has the characteristics of Carlin-type deposits, including: 1) an ore mineral assemblage consisting mostly of fine-grained pyrite, arsenian pyrite and arsenopyrite, 2) association of Au with As, Sb, Hg and Tl and high Au/Ag ratios, 3) a paragenesis that includes early Fe-As sulphides and kaolinite, intermediate stibnite and late baryte and 4) moderate to strong silicification and/or kaolinitization of rocks in ore zones and decarbonatization of silty carbonate rocks peripheral to faults. The Beast deposit is < 1 km from the Genesis deposit and 3 km from the huge Betze-Post deposit, and these and many other important deposits are located along the Post-Genesis fault system. The rhyolite dyke at Beast not only provides an important age constraint on Carlin-type mineralization in the Carlin trend but also gives information on the nature of mineralized rock largely free from earlier diagenetic, thermal or hydrothermal alteration experienced by Palaeozoic and Mesozoic rocks. Eocene dykes of the N Carlin trend, underlie or are immediately adjacent to a large (700 km2) positive aeromagnetic anomaly. The anomaly also corresponds closely with exposure of contemporaneous volcanic and intrusive rocks of the nearby 200 km2 Emigrant Pass volcanic field and smaller Welches Canyon centre. It is likely that the anomaly represents a buried, mainly Eocene, plutonic complex. [G.L.B.]
Sections:Economic minerals and ore deposits
Subsections:Metallic deposits: specific
Subjects:Carlin-type deposits; Cenozoic; Dikes; Eocene; Gold ores; Host rocks; Intrusions; Magmatism; Metal ores; Paleogene; Tertiary; Basin and Range Province; Carlin Trend; Elko County Nevada; Eureka County Nevada; Nevada; North America; United States; Beast Deposit
Coordinates:N391000 N410000 W1154500 W1163500
Abstract Numbers:03M/3747
Record ID:2001007884
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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