Diagenesis and ore deposition in sandstone-hosted uranium-vanadium deposits in the Colorado Plateau: Evidence from fluid inclusions

In order to better understand the diagenetic history of the U-V mineralization in the Morrison Formation of the Colorado Plateau, fluid inclusions trapped in authigenic calcites have been investigated. In the Cottonwood Wash district, Lisbon Valley area, Slick Rock district and Grants uranium region, fluid inclusion data indicate that temperatures near 100 deg. C have been reached. These temperatures correspond to maximum diagenesis of the host rocks. In the Lisbon Valley fault, fluid inclusions in calcite co-genetic with copper deposits contain solutions of variable salinities. Similar solutions were also present in the Slick Rock district. These solutions may have precipitated the vanadium chlorite, or influenced chlorite formation by recrystalization. In the Grants uranium region, fluid inclusion data support the model of Hansley on the alteration of primary ore deposits during maximum diagenesis and formation of altered ore. (author). 20 refs, 5 figs, 1 tab