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Uraniferous opal, Virgin Valley, Nevada: conditions of formation and implications for uranium exploration

Journal Article:

Abstract

Fission-track radiography shows uranium to be homogeneously dispersed throughout the opal structure, suggesting coprecipitation of dissolved uranium and silica gel. Fluid inclusions preserved within opal replacements of diatomite have homogenization temperatures in the epithermal range and are of low salinity. Four samples of opal from one locality all have U-Pb apparent ages which suggest uraniferous opal precipitation in late Pliocene time. These ages correspond to a period of local, normal faulting, and high-angle faults may have served as vertical conduits for transport of deep, thermalized ground water to shallower levels. Lateral migration of rising solutions occurred at intersections of faults with permeable strata. Silica and some uranium were dissolved from silica-rich host strata of 5-20 ppm original uranium content and reprecipitated as the solutions cooled. The model predicts that in similar geologic settings, ore-grade concentrations of uranium will occur in permeable strata that intersect high-angle faults and that contain uranium source rocks as well as efficient reductant traps for uranium. In the absence of sufficient quantities of reductant materials, uranium will be flushed from the system or will accumulate in low-grade disseminated hosts such as uraniferous opal.
Authors:
Zielinski, R A [1] 
  1. Geological Survey, Denver, CO (USA)
Publication Date:
Jan 01, 1981
Product Type:
Journal Article
Reference Number:
AIX-16-041349; EDB-85-083202
Resource Relation:
Journal Name: J. Geochem. Explor.; (Netherlands); Journal Volume: 16
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; NEVADA; URANIUM DEPOSITS; OPALS; NATURAL RADIOACTIVITY; URANIUM; NATURAL OCCURRENCE; AGE ESTIMATION; AQUEOUS SOLUTIONS; EXPLORATION; LEAD ISOTOPES; PRECIPITATION; URANIUM CONCENTRATES; URANIUM ISOTOPES; X-RAY DIFFRACTION; ACTINIDE ISOTOPES; ACTINIDES; CHALCOGENIDES; COHERENT SCATTERING; DIFFRACTION; DISPERSIONS; ELEMENTS; FEDERAL REGION IX; GEOLOGIC DEPOSITS; ISOTOPES; METALS; MINERAL RESOURCES; MINERALS; MIXTURES; NORTH AMERICA; ORE CONCENTRATES; ORES; OXIDE MINERALS; OXIDES; OXYGEN COMPOUNDS; RADIOACTIVITY; RESOURCES; SCATTERING; SEPARATION PROCESSES; SILICA; SILICON COMPOUNDS; SILICON OXIDES; SOLUTIONS; URANIUM ORES; USA; 050100* - Nuclear Fuels- Reserves, Exploration, & Mining
OSTI ID:
5740261
Country of Origin:
Netherlands
Language:
English
Other Identifying Numbers:
Journal ID: CODEN: JGCEA
Submitting Site:
HEDB
Size:
Pages: 197-216
Announcement Date:

Journal Article:

Citation Formats

Zielinski, R A. Uraniferous opal, Virgin Valley, Nevada: conditions of formation and implications for uranium exploration. Netherlands: N. p., 1981. Web.
Zielinski, R A. Uraniferous opal, Virgin Valley, Nevada: conditions of formation and implications for uranium exploration. Netherlands.
Zielinski, R A. 1981. "Uraniferous opal, Virgin Valley, Nevada: conditions of formation and implications for uranium exploration." Netherlands.
@misc{etde_5740261,
title = {Uraniferous opal, Virgin Valley, Nevada: conditions of formation and implications for uranium exploration}
author = {Zielinski, R A}
abstractNote = {Fission-track radiography shows uranium to be homogeneously dispersed throughout the opal structure, suggesting coprecipitation of dissolved uranium and silica gel. Fluid inclusions preserved within opal replacements of diatomite have homogenization temperatures in the epithermal range and are of low salinity. Four samples of opal from one locality all have U-Pb apparent ages which suggest uraniferous opal precipitation in late Pliocene time. These ages correspond to a period of local, normal faulting, and high-angle faults may have served as vertical conduits for transport of deep, thermalized ground water to shallower levels. Lateral migration of rising solutions occurred at intersections of faults with permeable strata. Silica and some uranium were dissolved from silica-rich host strata of 5-20 ppm original uranium content and reprecipitated as the solutions cooled. The model predicts that in similar geologic settings, ore-grade concentrations of uranium will occur in permeable strata that intersect high-angle faults and that contain uranium source rocks as well as efficient reductant traps for uranium. In the absence of sufficient quantities of reductant materials, uranium will be flushed from the system or will accumulate in low-grade disseminated hosts such as uraniferous opal.}
journal = {J. Geochem. Explor.; (Netherlands)}
volume = {16}
journal type = {AC}
place = {Netherlands}
year = {1981}
month = {Jan}
}