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At least 487 records · Page 27Linked to original sources
USGS1959

Gravity and seismic exploration in Yucca Valley, Nevada test site, January-April, 1959

The thickness of the alluvial and tuffaceous deposits that overlie bedrock in Yucca Valley has been inferred from gravity and seismic measurements. Preliminary interpretations indicate that these deposits are thickest in a narrow north-trending trough in the eastern part of the valley. The gravity data delineate a buried north-trending ridge of bedrock that extends from Mine Mountain almost to Quartzite Ridge. Seismic refraction measurements confirm the existence of the bedrock ridge and indicate that the bedrock is as close as 100 feet to the surface. The buried bedrock high is important because it may alter concepts of the movement of groundwater within the valley. A single seismic-refraction profile was located near the area of thickest alluvium and tuff to determine the feasibility of using refraction techniques for determining the depth to bedrock where it is covered with several thousand feet of alluvium and tuff. The results are encouraging but not enough data were acquired to give a reliable depth estimate. Seismic-refraction measurements were used successfully to determine the thickness of alluvium in narrow valleys partly filled with alluvium. This work was in the northwestern part of Yucca Valley and was done to choose drilling sites for studies of ground-water movement.

Nevada↗
USGS1955

Uranium deposits at the Jomac mine, White Canyon area, San Juan County, Utah

The Jomac mine is in the White Canyon area. San Juan County, Utah, about 13 miles northeast of the town of White Canyon, Utah. The mine is owned by the Ellihill Mining Company, White Canyon, Utah. Mine workings consist pf two adits connected by a crosscut. Two hundred feet of exploratory drifting and 2,983.5 feet of exploratory core drilling were completed during 1953 by the owners with Defense Minerals Exploration Administration assistance. Sedimentary rocks exposed in the area of the Jomac mine are of Permian to Late Triassic age, having a combined thickness of more than 1,700 feet. An ancient channel, from 200 to 400 feet wide and about 4 feet deep, enters the mine area from the southwest, swinging abruptly northwest near the mine workings and continuing to the northern tip of the Jomac Hillo This channel was cut into the upper beds of the Moenkopi formation and filled in part by Chinle and in part by Shinarump sediments. This channel is marked by depressions that apparently were scoured into its floor; a tributary channel may have joined it from the southeast at a point near the mine workings. Chinle beds Intertongue with Shinarump beds along the southwestern part of the channel. After the main channel was partly filled by siltstone of the Chinle formation, the stream was apparently diverted into the tributary channel, and scours were cut into the Chinle siltstone and filled by Shina'rump sandstone, conglomerate, and siltstone. Statistical study of wood orientation in the beds of the Shinarump conglomerate further indicates a channel trend of about N. 23° W. Basal siltstoned-pebble conglomerates appear to mark the edge of channels and scours. Jomac Hill is on the crest of a southwest-plunging fold that is on the west flank of a larger syncline. The area surrounding the hill is broken by intense faulting, but no faults were noted in the vicinity of the mine. The major fractures in the mine workings strike N. 70° to 80° E. and are steeply dipping. Secondary steeply dipping fractures strike N. 40° to 60 °E., and N. 10° E. to N. 10° W. The fractures are believed to be related to the anticlinal structure rather than the faults. Most of the uranium is contained in coa!5 associated with jarosite and gypsum in sandstone, conglomerate, or sandy siltstone near the base of the Shinarump conglomerate. Uranium occurs ill a fibrous green secondary mineral, metazeunerite, an unknown fibrous yellow mineral, and an unknown massive yellow mineral. Secondary copper minerals including malachite azurite, and chalcanthite occur locally with the uranium minerals. Principal ore guides at the Jomac mine are channels, and scours at the bottom of these channels coal-bearing sandstone or conglomerate at the base of the Shinarump conglomerate, coal, and jarosite.

Utah↗
USGS1955

Uranium-bearing minerals in placer deposits of the Red River Valley, Elk City district, Idaho County, Idaho

Uranium-bearing multiple oxide minerals were first recognized in the jig-bed concentrate of !the Tyee Mining Company'ss gold dredge on the Red River about 10 miles south of Elk City. Idaho County, Idaho, in late 1951 or early 1952. The gravels of the placer deposits were derived from the Idaho batholith and a roof pendant of Precambrian rocks in the batholith. Three samples taken for analysis show that the jig-bed concenuate contains 0.134 percent uranium. The nonmagnetic, non-radioactive fractions of the samples assayed 0.2 percent niobium, but no columbite was recognized in the samples. The uranium-bearing placer mineals are brannerite. euxenitte, davidite. betafite, and also contain niobium; ilmenite in the gravels may also contain some niobium. Pegmatites are believed to be the somce of the uranium- and niobium-bearing minerals, but the possibility of finding a pegmatite in the area ,that can be mined economically for uranium or niobium is remote.

Idaho↗
USGS1956

Machine for preparing phosphors for the fluorimetric determination of uranium

The time saved by use of a machine for preparing many phosphors at one time increases the rate of productivity of the fluorimetric method for determining uranium. The machine prepares 18 phosphors at a time and eliminates the tedious and time-consuming step of preparing them by hand, while improving the precision of the method in some localities. The machine consists of a ring burner over which the platinum dishes, containing uranium and flux, are rotated. By placing the machine in an inclined position the molten flux comes into contact with all surfaces within th dish as the dishes rotate over the flame. Precision is improved because the heating and cooling conditions are the same for each of the 18 phosphors in one run as well as for successive runs.

Trace Elements Investigations↗
USGS1956

Rapid-scanning microphotometry

A rapid-scanning microphotometer is described with which a 10-inch spectrum may be scanned in two minutes. The resulting chart may be 60, 300, or 1,500 cm long (wavelength scale) and 4 cm high (intensity scale). Commercially available components are used.

Trace Elements Investigations↗