Uranium deposits of Temple Mountain

Temple Mountain is a prominent topographic feature on the southeast flank of the San Rafael Swell in Emery County, Utah, the outline of which resembles the Temple at Salt Lake City. The existence of uranium in this area has been known for many years, but mining at Temple Mountain in the early part of this century was solely for radium and a little later for vanadium. Since 1947 a considerable amount of ore has been mined for the uranium and vanadium content. Information presented here was obtained in part from the geologic investigations connected with the study of the uranium deposits by the U. S. Geological Survey on behalf of the Division of Raw Materials of the U. S. Atomic Energy Commission.

110 FIFTH ANNUAL FIELD CONFERENCE 1 9 5 "' URANIUM DEPOSITS OF TEMPLE MOUNTAIN1 By RAYMOND C. ROBECK U. S. Geological Survey, Grand Junction, Colorado Temple Mountain is a prominent topographic fea­rure on the southeast flank of the San Rafael Swell in Emery County, Utah, the outline of which resembles the Temple at Salt Lake City. The existence of uranium in chis area has been known for many years, but mining at Temple Mountain in the early part of rhis century was solely for radium and a little later for vanadium. Since 1947 a considerable amount of ore has been mined for the uranium and vanadium content. Information presented here was obtained in part from the geologic investigations connected with the study of the uranium deposits by the U. S. Geological Survey on behalf of the Division of Raw Materials of the U. S. Aromic Energy Commission. The srrarigraphic section consists of beds of Tri­assic and Jurassic age. In ascending order these com­prise the Moenkopi formation, Shinarump conglomer­ate, Chinle formation, Wingate sandsrone, and Kayenta formation. The Shinarump as defined by Gilluly 1 Publication authorized by the Direcmr, U. S. Geological Survey. ( 1929) consists of a basal sandstone about 3 feet thick, a mudsrone approximately 10 to 20 feet thick, and a cliff-forming sandstone about 100 feet thick. Recent studies on the Colorado Plateau indicate that only the basal sandstone may be a direct correlative of the Shinarump of the type section near Kanab, Utah. The informal name of Moss Back sandstone is presently applied to the ore-bearing sandstone of the 100-foot cliff at Temple Mountain. For additional stratigraphic information refer to the paper by J. H. Stewart and J. Fred Smith, Jr., in this guidebook. Three east-west fault zones traverse the Temple Mountain area. One is exposed in the mines east of the Mountain, another is exposed l mile to the east, and a third l mile to the south of the Mountain. Sink holes and depressions, formed by the dissolv­ing of underlying formations, are present in the San Rafael Swell. The "Collapse Area" on Temple Moun­tain may be one of these features. The regional dip near Temple Mountain averages about 7° SE., but at the Collapse Area, the beds dip toward the center of PbotoK•apb hr Lew Well; I I I I I I I I I I I I I I I I I I I I Close-up of Temple Mountain uranium workings. Prominent sandstone above ore chute (center right) is I "Moss Back" sandstone unit of Chinle formation. Previously mapped as Shinarump conglomerate. 1 I I I I I I I I I I I I I I I I I I I - I INTERMOUNTAIN ASSOCIATION OF PETROLEUM GEOLOGISTS 111 the collapse. At least one large block each of so-called Moss Back and Wingate have dropped more than 100 feet below their original position. The core from a drill hole indicates that the Moss Back of local usage may possibly have fallen even deeper into a hole in the center of the Collapse Area. Subsequent erosion has removed most of the rock from the edge, but the rocks within the Collapse Area are present because secondary cementing made them more resistant. Other geologic features in the Collapse Area are: the bleach­ing of all the formations, the presence of native arsenic, the presence of goethite near the top of the Chinle, and the presence of uranium minerals in the so-called Moss Back sandstone, Chinle formation, and Wingate sandscone. The uranium and vanadium minerals that have been identified (Weeks and Thompson, in preparation) at or near Temple Mountain are: carnotite, hewettite, metatorbernite, rauvite, roscoelite, thucolite, tyuyamu­nite, uraninite, uvanite, and zippeite. Carbonized wood fragments, irregularly distributed in the sandstone, may or may not contain uranium. Carbon is present in botryoidal black pellets. Petroleum residue (asphalt) in sandstone appears co be polymer­ized to asphaltite, although viscous petroleum also has been found in several places at Temple Mouncain. Mining for uranium is presently confined to the so-called Moss Back sandstone where the ore is found as tabular bodies about 3 feet thick, as much as 200 feet long and 50 feet wide. The ore bodies trend northwest. These ore bodies are commonly in the lower 40 feet of the so-called Moss Back and the best ones are in the lower 20 feet. This 40-foot zone consists of incerfingering lenses of sandstone, mudscone, and con­glomerate, with uranium minerals commonly present only in the sandstone. As there is no persistent stratig· raphic unit within this zone, it is difficult to correlate adjacent ore bodies. LITERA TIJRE CITED Gilluly, James ( 1929), "Geology and Oil and Gas Prospects of Part of rhe San Rafael Swell, Utah," U. S. Geol. Survey Bull. 806-C. Weeks, A. D., and Thompson, M. E. (in preparation), "Identification and Occurrence of Uranium and Vanadium Minerals from the Colorado Plateau," U. S. Geo!. Survey Bull. 1009·B. I I l I I I I l PRvPt::H,·y vr· .808 0.WEN WHJTE INTERMOUNTAIN ASSOCIATION OF PETROLEUM GEOLOGISTS Geology of Portions of the High Plateaus and Adjacent Canyon Lands Central and South-Central Utah FIFTH ANNUAL FIELD CONFERENCE 1954