Wood River mining district, Idaho - intrusion-related lead-silver deposits derived from country rock source

Journal of Research of the U.S. Geological Survey
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Abstract

Lead-silver deposits in the Wood River mining district occur in shear zones in hornfelsed argillite of the Devonian Milligen Formation near granitic plutons and under the Wood River thrust fault. The principal ore minerals are argentiferous galena and sphalerite; siderite is the principal gangue. The δ34S values of the sulfide minerals range from +2.2 to +15.0 permil, indicating that the sulfur had a shallow crustal source. Δ34S values between sphalerite and galena range from +2.3 to +3.4 permil, corresponding to sulfur isotope temperatures between 280° and 182 °C. Hydrothermal barite has a δ34S of +13.2 permil. Lead isotope ratios are radiogenic, also pointing to a shallow crustal source. Quartz gangue has δ18O of +16.4 permil and a calculated δ18OH20 at 270°C of +8.4 permil. This value is reasonable for a hydrothermal fluid that had reached equilibrium with the argillite country rock. The siderite gangue has δ18O and δ13C values of +14.0 and -5.5 permil, respectively. Fluid inclusions have homogenization temperatures of 244°-307°C and average 270°C. Freezing-stage measurements ranged from -1.85 to -2.8°C, suggesting salinities of 3.2 to 4.8 weight percent. The δD values of inclusion fluid in ore and gangue minerals are -110 to -120 permil. The geology, isotope, and fluid-inclusion data are consistent with a model of hydrothermal systems of meteoric water in faulted and shattered Paleozoic rocks near plutonic masses. This environment permitted deep circulation of the hydrothermal fluids, which dissolved the metals and sulfur from the Paleozoic host rocks and deposited ore in favorable beds or structures under the regional Wood River thrust fault.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Wood River mining district, Idaho - intrusion-related lead-silver deposits derived from country rock source
Series title Journal of Research of the U.S. Geological Survey
Volume 6
Issue 5
Year Published 1978
Language English
Publisher U.S. Geological Survey
Publisher location Arlington, VA
Description 14 p.
First page 579
Last page 592
Country United States
State Idaho
County Blaine County
City Hailey, Bellevue
Other Geospatial Wood River
Online Only (Y/N) N
Additional Online Files (Y/N) N
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