Hydrothermal uranium vein deposits in Marysvale volcanic field, Utah
Hydrothermal uranium veins are exposed over a 300 m (980 ft) vertical range in mines of the Central Mining area, near Marysvale, Utah. They cut 23 Ma quartz monzonite, 21 Ma granite, and 19 Ma rhyolite ash-flow tuff. The veins formed 18-19 Ma, in an area 1 km (0.6 mi) across, above the center of a composite magma chamber at least 12 x 6 km across that fed a sequence of 21-14 Ma hypabyssal granitic stocks, and rhyolitic lava flows, ash-flow tuffs, and volcanic domes. Intrusive pressure uplifted and fractured the roof; molybdenite-bearing, uranium-rich glassy dikes were intruded; and a breccia pipe and uranium-bearing veins were formed. The veins appear to have been deposited near the surface above a concealed rhyolite stock, where they filled high-angle fault zones and flat-lying to concave-downward pull-apart fractures. Low pH and fO/sub 2/ hydrothermal fluids at temperatures near 200/sup 0/ C (392/sup 0/ F) permeated the fractured rocks; these fluids were rich in fluorine and potassium, and contained uranium as uranous-fluoride complexes. Fluid-wall rock interaction increased fluid pH, causing precipitation of uranium minerals. At the deepest exposed levels, wall rocks were altered to kaolinite and sericite, and uraninite, coffinite, jordisite, fluorite, molybdenite, quartz, and pyrite (with delta/sup 34/S near zero per mil) were deposited. The fluids were progressively oxidized higher in the system; iron in the wall rocks was oxidized to hematite, and sooty uraninite and umohoite were deposited.
- Research Organization:
- Energy Fuels Nuclear, Inc., Kanab, UT
- OSTI ID:
- 5502125
- Report Number(s):
- CONF-8408161-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 68:7; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
CHALCOGENIDES
COFFINITE
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
GEOLOGY
GRANITES
HYDROTHERMAL STAGE
IGNEOUS ROCKS
IRON COMPOUNDS
IRON SULFIDES
MATERIALS
MINERAL RESOURCES
MINERALS
NORTH AMERICA
ORIGIN
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
PLUTONIC ROCKS
PYRITE
QUARTZ
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
RESOURCES
RHYOLITES
ROCKS
SILICON COMPOUNDS
SILICON OXIDES
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
TUFF
URANINITES
URANIUM DEPOSITS
URANIUM MINERALS
USA
UTAH
VOLCANIC ROCKS