Geologic controls of uranium mineralization in the Tallahassee Creek uranium district, Fremont County, Colorado
Two important orebodies have been defined by drilling in the Tallahassee Creek uranium district, Fremont County, Colorado. They are the Hansen orebody, which contains about 12 million kg of U/sub 3/O/sub 8/, and the Picnic Tree orebody, which contains about 1 million kg of U/sub 3/O/sub 8/. Host rock for the Hansen is the upper Eocene Echo Park Alluvium, and host rock for the Picnic Tree is the lower Oligocene Tallahassee Creek onglomerate. Average ore grade for both deposits is about 0.08 percent U/sub 3/O/sub 8/. The principal source rock for the uranium depsoits is the lower Oligocene Wall Mountain Tuff, although a younger volcanic rock, the Oligocene Thirtynine Mile Andesite, and Precambrian granitic rocks probably also contributed some uranium. Leaching and transportation of the uranium occurred in alkaline oxidizing ground water that developed during alteration of the ash in a semi-arid environment. The uranium was transported in the ground water to favorable sites where it was deposited in a reducing environment controlled by carbonaceous material and associated pyrite. Localization of the ore was controlled by ground-water flow conditions and by the distribution of organic matter in the host rock. Ground-water flow, which was apparently to the southeast in Echo Park Alluvium that is confined in the Echo Park graben, was impeded by a fault that offsets the southern end of the graben. This offset prevented efficient discharge into the ancestral Arkansas River drainage, and protected chemically reducing areas from destruction by the influx of large amounts of oxidizing ground water. The location of orebodies in the Echo Park Alluvium also may be related to areas where overlying rocks of low permeability were breached by erosion during deposition of the fluvial Tallahassee Creek Conglomerate allowing localized entry of uranium-bearing water.
- Research Organization:
- Geological Survey, Denver, CO
- OSTI ID:
- 5902285
- Journal Information:
- Mt. Geol.; (United States), Vol. 18:4
- Country of Publication:
- United States
- Language:
- English
Similar Records
Detailed uranium hydrogeochemical and stream sediment reconnaissance of the Tallahassee Creek, Badger Creek, Castle Rock Gulch, and Buffalo Gulch areas in the northwestern part of the Pueblo NTMS Quadrangle, Colorado
Origin and significance of organic matter in uranium deposits of Morrison Formation, San Juan Basin, New Mexico
Related Subjects
COLORADO
URANIUM DEPOSITS
GEOLOGY
MINERALIZATION
CONGLOMERATES
GRANITES
ORIGIN
SEDIMENTARY ROCKS
SOURCE ROCKS
TERTIARY PERIOD
TUFF
CENOZOIC ERA
GEOLOGIC AGES
GEOLOGIC DEPOSITS
IGNEOUS ROCKS
MINERAL RESOURCES
NORTH AMERICA
PLUTONIC ROCKS
RESOURCES
ROCKS
ROCKY MOUNTAIN REGION
USA
050100* - Nuclear Fuels- Reserves
Exploration
& Mining