GEOCHEMISTRY OF THE FRENCHY INCLINE URANIUM DEPOSIT, SAN MIGUEL COUNTY, COLORADO

Journal Article · Thu Mar 01 04:00:00 EST 1962 · Dissertation Abstr.

OSTI ID:4804995

Miesch, A T

4 : chy Incline uranium deposit is in the Salt Wash member of the Morrison formation on the central part of the Colorado Plateau, and consists of sandstone and mudstone impregnated with uranium and vanadium minerals in addition to other constituents. The compositions of the deposit and its host rocks are determined from semiquantitative spectrographic analyses of 2l9 drill-core samples. Comparison of the compositions of the mineralized and unmineralized rocks shows that in the formation of the deposit the host rocks are enriched in vanadium, iron, uranium, strontium (?), lead, zinc, copper, chromium (?), nickel, cobalt, molybdenum, and silver, in decreasing order of abundance. In general, this is the same suite of elements found to be enriched in other uranium deposits in the Salt Wash member of the Morrison formation on the Colorado Plateau. Quantitative considerations show that most of the enriched elements in the Frenchy Incline deposit could be derived from altered sandstone adjacent to the deposit without changing its composition by any detectable amount. However, uranium and probably vanadium are derived from sources external to the altered part of the sandstone lens in which the deposit occurs; an unknown amount of lead in the deposit originates from the radioactive decay of uranium within the deposit. lf the elements are transported to the deposit by flowing ore solutions, the required minimum concentration of each element in the solution depends on the volume of the solution that passes through the deposit. Assuming that the hydraulic gradient that causes solution flow results from differences in hydrostatic head caused only by the dip of the aquifer, the msximum volume of the solution passing through the deposit per unit time, for a given structural gradient, may be estimated from Darcy's law. The required minimum concentration of each element in the ore solution, then, becomes a function of the duration of mineralization and the structural gradient. Probably not all elements that are enriched in the deposit are transferred to the site of mineralization by flowing solutions. Thermodynamic considerations suggest that concentration gradients of iron in solution are established in the host sandstone during an early period of relatively stagnant ground-water conditions. Iron and other elements any be transferred by solute diffusion processes occurring in response to the concentration gradients. The regional variations of elements among other uranium deposits in the Salt Wash member point to the sources of these elements in the deposits. It is interpreted that iron, molylbdenum, colbalt, nickel, selenium, arsenic, and part of the zinc in the deposits are derived chiefly from tuffaceous materials in or associated with the host sandstone. Some copper, silver, and lead in the deposits may also be derived from the host sandstone. Additional copper, silver, lead, and part of the zinc are derived from sources external to the Salt Wash member by way of fractures in the salt anticline region of western Colorado and eastern Utah. Vanadium in the deposits may be derived from heavy minerals in the host sandstone, but not from the altered part of the lens in which the deposit occurs. Uranium in the Frenchy Incline deposit, and in other deposits in the Salt Wash member, may be derived from magmatic sources that produce the laccoliths of the La Sal Mountains, from extensive tuffaceous accumulations in the Morrison formation, or from other souices. It is possible that uranium precipitates from solution on the reduction of uranyl ions by earlier accumulations of pyrite. An hypothesis of origin for the Frenchy Incline uranium deposit is given that involves at least two stages of mineralization. The hypothesis accounts for the regional distributions of elements in the uranium deposits of the Salt Wash member over the entire Colorado Plateau, and interprets the deposits as resulting from the interaction of dynamic and chemical processes. The dynamic processes control hydrologic condi

• Research Organization: Northwestern Univ., Evanston, Ill.
• NSA Number: NSA-16-027438
• OSTI ID: 4804995
• Journal Information: Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 22
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CHROMIUM
CLAYS
COBALT
COLORADO
COPPER
DECAY
DEPOSITS
DISTRIBUTION
ENRICHMENT
GEOCHEMISTRY
GEOLOGY, MINERALOGY, AND METEOROLOGY
GROUND WATER
HYDRAULICS
HYDROLOGY
IRON
IRON SULFIDES
LEAD
LIQUID FLOW
MINERALS
MOLYBDENUM
MUD
NICKEL
ORES
PRECIPITATION
PYRITE
QUANTITY RATIO
REDUCTION
ROCKS
SAND
SILVER
SLURRIES
SOLUTIONS
SPECTROSCOPY
STRONTIUM
THERMODYNAMICS
TUFF
URANIUM
URANIUM MINERALS
URANIUM ORES
URANYL COMPOUNDS
USA
VANADIUM
WELL LOGGING
ZINC