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ALTERATION STUDIES AND URANIUM EMPLACEMENT NEAR MOAB, UTAH: PART I. HYDROTHERMAL ALTERATION ALONG THE LISBON VALLEY FAULT ZONE, SAN JUAN COUNTY, UTAH. PART II. ALTERATION STUDIES OF CUTLER AND CHINLE STRATA ALONG LISBON VALLEY ANTICLINE, SAN JUAN COUNTY, UTAH. PART III. A REVIEW OF LEAD/URANIUM AND SULPHUR ISOTOPE DATA FOR LISBON VALLEY, UTAH. PART IV. ALTERATION IN CULTER STR

Thesis/Dissertation ·
OSTI ID:4017424

In order to identify the mineralogical changes recorded in sediments from the passage of ore solutions, relevant specimens from Cutier and Chinle strata associated with uranium deposits on Lisbon Valley and Cane Creek anticlines were studied in detail. A major fault follows the crest of the Lisbon Valley salt anticline and strikes northwest across the Big Indian Wash uranium area. Solution activity in the fault zone is indicated by bleaching and silicification. Argillic mineral associations, fracturecontrolled copper sulphide deposits, and indurated hydrocarbons indicate that the mineralizing solutions were heated. Bleaching near fractures and in porous Cutler strata on Lisbon Valley anticline, known locally as sugar sands,'' is demonstrated to show solution movement through these strata. In sugar sands close to Lisbon Valley fault, feldspar and biotite are altered to kaolinite and biotite is replaced by interleaved lenses of calcite. The alteration is interpreted as the result of hydrothermal activity, which is marked by the work of diffusing solutions on selective minerals, often leaving them incompletely changed. Sugar sands southeast of the Lisbon Valley fault have a mixedlayer clay content, which represents an intermediate stage in the alteration of mica and chlorite to clay. It is suggested that the system of faults, fractures, and porous stratigraphic conduits extended laterally and vertically to distant reaches and provided ease of movement for mineralizing solutions. Available lead/uranium and sulfur isotope data for the Lisbon Valley uranium area, Utah, were reviewed from the standpoint of their bearing on interpretation of the mechanism of uranium emplacement. In Cane Creek area, several mineralized high angle faults closely parallel the northwest trending anticlinal axis, and are mineralized with uraninite, secondary uranium minerals, and associated organic material. Intense bleaching of red beds occurs near faults and fractures, and extends into adjoining strata. The fault-controlled uranium deposition is interpreted as having been caused by the reduction of uranium-bearing solutions by hydrogen suifide derived in part from petroleum, which migrated upward along fractures, as well as from decaying organic material. Extensive activity of solutions along fractures is evident and suggests a motivating hydrothermal source, an aftermath of igneous intrusions known to penetrate the Plateau sediments, such as in the LaSal stocks and loccoliths. (Dissentation Abstr., 24: No. 9, March 1964)

Research Organization:
Originating Research Org. not identified
NSA Number:
NSA-18-020228
OSTI ID:
4017424
Country of Publication:
Country unknown/Code not available
Language:
English