Preliminary study of uranium favorability of the Boulder batholith, Montana
The Boulder batholith of southwestern Montana is a composite Late Cretaceous intrusive mass, mostly composed of quartz monzonite and granodiorite. This study was not restricted to the plutonic rocks; it also includes younger rocks that overlie the batholith, and older rocks that it intrudes. The Boulder batholith area has good overall potential for economic uranium deposits, because its geology is similar to that of areas that contain economic deposits elsewhere in the world, and because at least 35 uranium occurrences of several different types are present. Potential is greatest for the occurrence of small uranium deposits in chalcedony veins and base-metal sulfide veins. Three areas may be favorable for large, low-grade deposits consisting of a number of closely spaced chalcedony veins and enriched wall rock; the Mooney claims, the Boulder area, and the Clancy area. In addition, there is a good possibility of by-product uranium production from phosphatic black shales in the project area. The potential for uranium deposits in breccia masses that cut prebatholith rocks, in manganese-quartz veins near Butte, and in a shear zone that cuts Tertiary rhyolite near Helena cannot be determined on the basis of available information. Low-grade, disseminated, primary uranium concentrations similar to porphyry deposits proposed by Armstrong (1974) may exist in the Boulder batholith, but the primary uranium content of most batholith rocks is low. The geologic environment adjacent to the Boulder batholith is similar in places to that at the Midnite mine in Washington. Some igneous rocks in the project area contain more than 10 ppM U/sub 3/O/sub 8/, and some metasedimentary rocks near the batholith contain reductants such as sulfides and carbonaceous material.
- Research Organization:
- Bendix Field Engineering Corp., Grand Junction, Colo. (USA)
- DOE Contract Number:
- EY-76-C-13-1664
- OSTI ID:
- 5203972
- Report Number(s):
- GJBX-5(78); TRN: 78-005761
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MONTANA
URANIUM DEPOSITS
EXPLORATION
ABUNDANCE
BLACK SHALES
CARBONACEOUS MATERIALS
CRETACEOUS PERIOD
GRANODIORITES
IGNEOUS ROCKS
QUARTZ
SILICON OXIDES
SULFIDES
URANIUM OXIDES U3O8
ACTINIDE COMPOUNDS
BITUMINOUS MATERIALS
CHALCOGENIDES
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MESOZOIC ERA
NORTH AMERICA
OIL SHALES
OXIDES
OXYGEN COMPOUNDS
ROCKS
SILICON COMPOUNDS
SULFUR COMPOUNDS
URANIUM COMPOUNDS
URANIUM OXIDES
USA
050200* - Nuclear Fuels- Exploration- (-1987)