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Research about San Miguel County, Colorado

Source-linked reports with geographic coverage including San Miguel County, Colorado.

At least 19 recordsLinked to original sources
USGS1963

Fossils from lower part of the Mancos Shale, Disappointment Valley, San Miguel County, Colorado

About 400 fossiliferous segments of drill core from the lower part of the Mancos Shale of Late Cretaceous age were collected by the author during an exploratory drilling program for uranium deposits conducted in 1955 and 1956 by the Geological Survey in the Disappointment Valley area, San Miguel County, Colo. "The samples were submitted to the late J. B. Reeside, Jr., of the Geological Survey for identification. Reeside's identifications are being released in open file in order to make them available to those interested.

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USGS1962

Exploration for uranium-vanadium deposits by U.S. Geological Survey 1948-56 in western Disappointment Valley area, Slick Rock district, San Miguel County, Colorado

The western Disappointment Valley area is in San Miguel County, Colo., in the northeastern part of the Slick Rock district, (see location map). It covers an area of approximately 50 square miles in Tps. 43 and 44 N., Rs. 17, 18, and 19 W., New Mexico principal meridian. The mining camp of Slick Rock is in the western part of the area. On the northeast the area is bounded by Gypsum Valley; the other boundaries are arbitrarily drawn to delimit the area in which drilling was done.

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USGS1961

Geochemistry of the Frenchy Incline uranium deposit, San Miguel County, Colorado

The Frenchy 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 that have been impregnated with uranium and vanadium minerals in addition to other constituents. The compositions of the deposit and its host rocks have been determined from semiquantitative spectrographic analyses of 219 drill-core samples. Comparison of the compositions of the mineralized and unmineralized rocks shows that in the formation of the deposit the host rocks were 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 which has been found to be enriched in other uranium deposits in the Salt Wash member of the Morrison formation on the Colorado Plateau.

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USGS1958

Areal geology of the Little Cone quadrangle, Colorado

The Little Cone quadrangle includes an area of about 59 square miles in eastern San Miguel County in southwestern Colorado. It lies within and adjacent to the northeastern boundary of the Colorado Plateau physiographic province. The precipitous front of the San Juan Mountains lies a few miles to the east and northeast, and an outlier of the San Juans, the San Miguel Mountains, lies about a mile to the south. The quadrangle contains features characteristic of both the plateaus and the mountains, and has been affected by geologic events and processes of two different geologic environments.

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USGS1953

Carnotite resources of the Spud Patch area, San Miguel County, Colorado

The Spud Patch area comprises about 8 square in T. 43 M., R. 18 and 19 W., San Miguel County, Colo., and is about 4 miles northeast of Egnar, Colo. Claims of the United States Vanadium Co. and the Vanadium Corp. of America cover about half the area. Claims of other owners, public land, and patented agricultural land, comprise the remainder of the area. The area is about 38 miles from the Government mill at Montecello, Utah, and 55 miles from the Vanadium Corp. of America mill at Naturita, Colo. Between 1940 and 1951, the Spud Patch area yielded about 24,000 short tons of carnotite ore that probably averaged 0.21 percent U 3 O 8 and 2.2 percent V 2 O 5 . The deposits are in a broad sandstone lens near the top of the Salt Wash member of the Jurassic Morrison formation. Although the deposits mined have been mainly impregnations of sandstone by carnotite and gray vanadium-bearing clay minerals, some of the richer deposits found by Geological Survey drilling have a finely disseminated black uranium mineral but no carnotite. The deposits commonly are thin irregular tabular layers, which locally thicken to form elongate masses called "rolls". These rolls have a dominant northeasterly trend. Geologic features found to be most useful as guides to ore are listed. From November 1949 to May 1952, the U.S. Geological Survey drilled 415 diamond-drill holes totaling 67,215 feet in the Spud Patch area. The purpose of this drilling was to find deposits that would make new mines and to appraise the reserves in the unexplored area. As a result of Geological Survey drilling, indicated and inferred reserves computed at the cutoff of 1 foot or more thick and 0.10 percent U 3 O 8 or 1.0 percent V 2 O 5 total 20,500 short tons, averaging 0.28 percent U 3 O 8 and 2.1 percent V 2 O 5 . These reserves and those computed at a lower grade cutoff of 0.05 percent U 3 O 8 or 0.50 percent V 2 O 5 and the pounds of contained metal are summarized in table 1. Potential reserves, whose existence is based on geologic evidence alone, are predicted to total about 42,000 short tons, averaging 0.25 percent U 3 O 8 and 2.0 percent V 2 O 5 . No additional exploratory-type drilling by the Geological Survey is planned in the Spud Patch area. Recommendations are offered for additional development-type drilling, preferably by claim owners or lessees in specific areas in the vicinity of deposits discovered by Geological Survey drilling.

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USGS1951

Carnotite resources of the upper group area, San Miguel County, Colorado

The Upper group area, which consists of 10 Government claims and adjoining public land, is 2 miles southeast of Slick Rock, San Miguel County, Colo., in unsurveyed secs. 5 and 6, T. 43 N., R. 18 W., New Mexico principal meridian. The area is equidistant from mills at Monticello, Utah, and Naturita, Colo. Both mills are reached by about 45 miles of all-weather roads. About 2,700 tons of carnotite ore was produced from the area between 1921 and 1943 (tons used in this report are short tons). This ore had an estimated average grade of 0.25 percent U30g and 1.7 percent V205. The ore deposits are in the top sandstone stratum of the Salt Wash sandstone member of the Tipper Jurassic Morrison formation. The principal ore-bearing minerals, which mainly impregnate the sandstone, consist of uranium-bearing carnotite and a micaceous vanadium-bearing mineral called “roscoelite." The deposits are mostly in small podlike masses called "rolls." The size of the rolls ranges from less than 50 to more than 1,500 tons each. The long axes of the rolls have a dominant northeasterly to easterly trend. Exploration by the Geological Survey was done on behalf of the Atomic Energy Commission to test unexplored ground for new deposits of carnotite ore and to gain a better appraisal of the reserves in the area. From 1948 to 1950, 186 diamond-drill holes were completed for a total of 14,577 feet. The areas of favorable sandstone were found and defined by holes drilled 300 to 500 feet apart. Altered mudstone, carbonaceous material in the sandstone, and color of the sandstone were used to determine the favorability of the sandstone. Within areas containing favorable sandstone holes were drilled on 100- to 150-foot centers to find deposits. Where deposits were found more than 20 feet below the surface, they were roughly outlined by holes drilled on 50- to 75- foot centers. Deposits discovered within 20 feet of the surface were not outlined. Reserves in deposits found by the drilling are classed as indicated and inferred, whereas those reserves that are predicted solely on geologic evidence are classed as potential. Indicated reserves computed at the highest thickness and grade cut-offs (1 foot or more thick and 0.10 percent U3O8 or .10 percent V205) total 5,000 tons, averaging 0.19 percent U308 and 1.6 percent V205. Inferred reserves computed at the same cut-offs total 3,500 tons, averaging .22 percent U308 and 1.7 percent V205. Both the indicated and inferred reserves, as well as the pounds of contained U3O8and V205, are summarized in table 1. Potential reserves are predicted to total about 1,500 tons, averaging about 0.20 percent U3O8 and 1.6 percent V205. Most of the potential reserves are expected to be in small scattered deposits within 20 feet of the surface. No additional diamond drilling by the Geological Survey is planned in the Upper group area. Several specific localities, principally in the central part of the area, are recommended for further exploration by jackhammer and wagon drilling by lessees and operators.

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USGS1950

Carnotite resources in the Charles T. area and vicinity, San Miguel County, Colorado

Between November 1947 and September 1949, the United States Geological Survey, at the request of the Atomic Energy Commission, conducted an exploratory drilling program in the Charles T. area and vicinity. The purpose of the exploration was to discover new carnotite deposits to support milling operations on the Colorado Plateau, and to appraise the uranium and vanadium resources of the area explored.

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USGS1950

Distribution of leached radioactive material in the Legin Group Area, San Miguel County, Colorado

Radioactivity anomalies, which are small in magnitude, and probably are not caused by extensions of known uranium-vanadium ore bodies, were detected during the gamma-ray logging of diamond-drill holes in the Legin group of claims, southwest San Miguel County, Colo. The positions of these anomalies are at the top surfaces of mudstone strata within, and at the base of, the ore-bearing sandstone of the Salt Wash member of the Morrison formation. The distribution of these anomalies suggests that ground water has leached radioactive material from the ore bodies and has carried it down dip and laterally along the top surfaces of underlying impermeable mudstone strata for distance as great as 300 feet. The anomalies are probably caused by radon and its daughter elements. Preliminary tests indicate that radon in quantities up to 10 -7 curies per liter may be present in ground water flowing along sandstone-mudstone contacts under carnotite ore bodies. In comparison, the radium content of the same water is less than 10 -10 curies per liter. Further substantiation of the relationship between ore bodies, the movement of water, and the radon-caused anomalies may greatly increase the scope of gamma-ray logs of drill holes as an aid to prospecting.

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