Sedimentology of the Westwater Canyon and Brushy Basin Members, Upper Jurassic Morrison Formation, Colorado Plateau, and relationship to uranium mineralization
The Westwater Canyon Member was deposited by eastward-flowing, high energy, intermittent streams that drained a source area of diverse lithologies. Multi-channel river systems exhibited only minor downstream changes, most notably a slight increase in the amount of lateral accretion deposition. During deposition of the overlying Brushy Basin Member, a large saline, alkaline lake developed in an area that encompasses both the San Juan basin and the Paradox basin. Alteration of airborne volcanic ash that became incorporated in the lake sediments resulted in a lateral zonation of authigenic minerals that resembles the zonation characteristic of Cenozoic saline, alkaline lakes. The lake, named Lake T'oo'dichi, is the largest and oldest saline, alkaline lake known. Localization of primary uranium ore in the Grants uranium region, New Mexico, is more related to depositional facies in the Brushy Basin Member than to any special attribute of the host sandstones in the Westwater Canyon Member. Coincidence of depositional facies in the Brushy Basin Member with ore distribution and ore-related alteration patterns in the Westwater Canyon Member suggests a model in which humic acids originated in pore waters of smectitic mudstones of the Brushy Basin Member and moved downward into the underlying sandstones of the Westwater Canyon Member. Here, the humic acids precipitated to form humin layers that subsequently concentrated uranium from ground water to form the orebodies.
- Research Organization:
- Colorado Univ., Boulder (USA)
- OSTI ID:
- 5904243
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Exploration
& Mining
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
COLORADO
DEPOSITION
FEDERAL REGION VI
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGIC MODELS
HUMIC ACIDS
IGNEOUS ROCKS
JURASSIC PERIOD
LAKES
MESOZOIC ERA
MINERAL RESOURCES
MINERALIZATION
NEW MEXICO
NORTH AMERICA
ORES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORIGIN
PH VALUE
RESOURCES
RIVERS
ROCKS
SALINITY
SANDSTONES
SEDIMENTARY ROCKS
SEDIMENTS
STREAMS
SURFACE WATERS
URANIUM DEPOSITS
URANIUM ORES
USA
VOLCANIC ROCKS