Deposits of copper, vanadium, and uranium in nonmarine sandstones are numerous and widespread. Copper deposits, with or without uranium, are mainly resident in first-generation arkosic sandstones derived from granitic rock terrains; deposits rich in vanadium, with or without much uranium, are dominantly in second-generation sandstones derived from sedimentary rocks; and the uranium deposits with little or no vanadium or copper are in either first- or second-generation sandstones, many of which are associated with beds containing volcanic debris. All three metals are dispersed in igneous rocks but not in close association. Copper and uranium enter the hydrothermal environment, but the record of vanadium in hydrothermal solutions and veins is scant. Some of the uranium and most of the copper minerals in igneous rocks and veins oxidize readily and the metals go into surface- and ground-water solutions, but the vanadium in igneous rocks is not so easily mobilized-under normal geologic conditions, conceivably it may require diagenetic reactions and a second period of weathering to solubilize much vanadium. All three metals precipitate from solutions in the presence of a reducing agent, such as carbonaceous material or associated sulfide ions, either in sediments as they accumulate or in existing rocks. These geochemical habits permit the concept that copper and uranium are made available by weathering of igneous rock terrains and hence might accumulate in first-generation sediments, whereas vanadium would be commonly available only after a second period of weathering. Perhaps the oxidation or devitrification of volcanic debris may contribute uranium to ground waters as does the weathering, of igneous rocks.
|Publication Subtype||Journal Article|
|Title||Copper, vanadium, and uranium deposits in sandstone-their distribution and geochemical cycles|
|Series title||Economic Geology|
|Publisher||Society of Economic Geologists|
|Google Analytic Metrics||Metrics page|