Uranium Deposits

Geography of U Deposits – USAStates with mineable resources

States currently producing U3O8

Geography of major U Deposits – USA

North Dakota’s Uranium Deposits

Sedimentary Host Rocks

• Sandstones and Arkoses– Porous– Permeable– Lower pH than incoming water

• Coal and lignite beds– Also have low pH compared to inflowing water

Sedimentary-hosted Uranium Deposits

• Very high tonnage but lower grade (compared to unconformity type)

• U transported by ground water

• U deposited as water encounters a reducing environment (organic matter or gas, sulfide minerals)

• Drop in pH results in precipitation of U minerals in pore spaces.

Prerequisites for a Sedimentary-hosted Uranium deposit

1) Source of U2) Coarse sands with good porosity and

permeability3) Ground water flow (naturally oxygenated) –

ideally channelized, high rate of flow4) Reduction zone – heavy minerals, decaying

organic matter

Uranium Deposit host RocksWasatch Formation - PRB

Fort Union Formation - PRB

Wind River Formation, Puddle Springs Member – Gas Hills

Wind River FormationShirley Basin

Battle Spring FormationGreat Divide Basin