GEOCHEMICAL STUDIES OF MINERAL DEPOSITS IN THE LISBON VALLEY AREA, SAN JUAN COUNTY, UTAH

Journal Article · Wed Feb 28 23:00:00 EST 1962 · Dissertation Abstr.

OSTI ID:4805028

Kennedy, V C

A geochemical study is made of uranium-vanadium, copper, and manganese deposits in the Lisbon Valley area from 1954 to 1957. The composition of the various types of ore is determined and the information is combined with mineralogic and geologic data to evaluate various hypotheses of ore genesis. Uranium-vanadium deposits occur as generally tabular bodies in or near sandstones of the Permian Cutler formation, the Triassic Chinle formation, and the Salt Wash member of the Jurassic Morrison formation. The Cutler ores contain uranium, vanadium, copper, barium, and lesser-but still anomalous-concentrations of cerium, dysprosium, erbium, germanium, holmium, lanthanum, lead, niobium, neodymium, silver, and yttrium. Copper concentrations are highest in Cutier ore near the Lisbon Valley fault. Large deposits of basal Chinle sandstones lie along the southwest flank of the Lisbon Valley anticline. These deposits consist mainly of uranium and vanadium but contain anomalous concentrations of arsenic, barium, beryllium, cadmium, cobalt, copper, iron, lead, molybdenum, nickel, some rare earths, selenium, strontium, thallium, zinc, and zirconium. The vanadium:uranium ratio is highest in the southeastern Chinle ores and decreases northwestward. This ratio also decreases down dip, possibly because of selective leaching of uranium. Arsenic, molybdenum, and yttrium are most concentrated in the southeastern deposits; cadmium and copper in the middle area, and strontium and beryllium in the northwestern deposits. The ore-associated elements in Chinle deposits show only a poor correlation with uranium, except for lead. The uranium:lead ratio is relatively consistent and averages approximately 33:1. Assuming that very little common or old radiogenic lead is present, the uranium:lead ratio indicates an apparent age of the ores of about 225 million years. Corrections for alteration of the ore might give an age in the range indicated by some isotopic data, that is 180 to 190 million years. Comparison of barren and mineralized Salt Wash sandstones indicates that arsenic, barium, beryllium, calcium, cobalt, copper, lead, manganese, molybdenum, strontium, uranium, vanadium, yttrium, and zinc are enriched in one or more mineralized samples. The Rattlesnake deposit, which is cut by the Lisbon Valley fault, contains more selenium than other Salt Wash ores analyzed. In the southeastern part of the Lisbon Valley area copper mineials are more common in Salt Wash deposits within about a mile of the Lisbon Valley fault than they are elsewhere. Otherwise no evidence of chemical zoning is noted. Copper minerals occur mainly in veins and bedded deposits near the Lisbon Valley fault zone, but are present in minor amounts in some uranium-vanadium deposits several miles from the fault. Copper-bearing veins also cut altered diorite porphyry in the La Sal Mountains. The copper deposits vary somewhat in composition, but most contain arsenic, barium, molybdenum, selenium, and silver. Manganese oxides are present as vein fillings and disseminated deposits along the Lisbon Valley fault. Compared to barren sandstones the manganese ores are enriched in arsenic, barium, cobalt, copper, molybdenum, selenium, silver, strontium, vanadium, and zinc. The genesis of the uranium-vanadium ores is believed to be different from that of the copper and manganese ores. The latter are thought to have been deposited mainly from solutions circulating along and spreading outward from fault zones. Most copper ores are not older than the Cretaceous, and the Chinle uranium-vanadium deposits seem to be of Triassic or Early Jurassic age. Because connate waters squeezed from red beds during compaction must have passed through the sites of present uranium-vanadium deposits and because it seems possible that these fluids could have carried the ore elements in solution, connate waters are believed to have constituted the ore fluid.

• Research Organization: Univ. of Colorado, Boulder
• NSA Number: NSA-16-027437
• OSTI ID: 4805028
• Journal Information: Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 22
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AGE ESTIMATION
ARSENIC
BARIUM
BERYLLIUM
CADMIUM
CALCIUM
CERIUM
COBALT
CONFIGURATION
COPPER
DECAY
DEPOSITS
DIORIT
DISTRIBUTION
DYSPROSIUM
ENRICHMENT
ERBIUM
GEOCHEMISTRY
GEOLOGY
GEOLOGY, MINERALOGY, AND METEOROLOGY
GERMANIUM
HOLMIUM
IGNEOUS ROCKS
IRON
LANTHANUM
LEAD
MANGANESE
MINERALS
MOLYBDENUM
NEODYMIUM
NICKEL
NIOBIUM
ORES
PORPHYRINS
RARE EARTHS
ROCKS
SAND
SELENIUM
SILVER
SOLUTIONS
STRONTIUM
THALLIUM
URANIUM
URANIUM MINERALS
URANIUM ORES
USA
UTAH
VANADIUM
YTTRIUM
ZINC
ZIRCONIUM
ZONES