Reports of the Alaska Division of Geological and Geophysical Surveys and predecessor agencies, 1913-1973, indexed by quadrangle
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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
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No abstract available.
National energy needs have precipitated an increased interest in the development of a large coal-based electric power industry in the western United States. This anticipated development has, in turn, spawned a great deal of interest in the environmental impact consequent upon the mining and utilization of these coal supplies. Numerous studies directed to assessing this impact are underway or are in the planning stages by agencies of government at all levels as well as by educational institutions and private firms. It is expected that such studies will continue to increase in number in the foreseeable future. Some idea of the diversity of this work is given by Boulding (1974), who surveyed a broad spectrum of people and organizations concerned about the environmental impact of coal development in the Northern Great Plains. This survey included over 50 governmental organizations and over 50 nongovernmental organizations.
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Ten core samples of two rich oil-shale beds from the Parachute Creek Member of the Eocene Green River Formation, Piceance Creek basin, Colorado, and Uinta Basin, Utah, were analyzed for 34 major, minor, and trace elements. For 23 of these elements, principal mineralogical residence is established or suggested. Such studies of distribution and mineralogical residence provide important data for predicting the kinds and amounts of elements and compounds--some possibly harmful-that might he released into the environment by oil-shale mining operations. However, because of the many variables involved, no attempt is made to discuss these results in terms of any of the various retorting methods.
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A High-Gain, Long-Period Seismograph System was installed at Matsushiro, Japan, during November and December 1972. The system consists of two horizontal and one vertical seismometer with natural periods of 30 seconds. Each seismometer contains two velocity transducers and one displacement transducer.
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A High-Gain, Long-Period Seismograph System, developed by the Lamont-Doherty Geological Observatory, was installed at the Kipapa site of the Honolulu Observatory near Ewa Beach, Oahu, Hawaii in March 1972. Magnifications of 55,000 for the vertical component and 40,000 for the horizontal components were obtained. Velocity data are recorded both photographically and digitally. Displacement data are recorded digitally.
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The Midnite mine is one of only two mines in the United States currently producing uranium from discordant deposits in crystalline host rocks. Ore bodies are in metamorphosed steeply dipping Precambrian pelitic and calcareous rocks of a roof pendant adjacent to a Cretaceous(?) porphyritic quartz monzonite pluton. Production during 14 years, of operation has been about 8 million pounds of U3O8 from oxidized and reduced ores averaging 0.23 percent U3O8. Uranium deposits are generally tabular in form and dimensions range up to 380 m long, 210 m wide, and 50 m thick. Deposits are bounded on at least one side by unmineralized intrusive ribs of granitic rock, and thickest mineralized zones invariably occur at depressions in the intrusive contact. Upper limits of some deposits are nearly horizontal, and upper elevations of adjacent mineralized zones separated by ribs of granite are similar. Near surface ore is predominantly autunite, but ore at depth consists of pitchblende and coffinite with abundant pyrite and marcasite. Uranium minerals occur as .disseminations along foliation, replacements, and stockwork fracture-fillings. No stratigraphic controls on ore deposition are recognized. Rather, mineralized zones cut across lithologic boundaries if permeability is adequate. Most ore is in muscovite schist and mica phyllite, but important deposits occur in calc-silicate hornfels. Amphibolite sills and mid-Tertiary dacite dikes locally, carry ore where intensely fractured. High content of iron and sulfur, contained chiefly in FeS2, appear to be an important feature of favorable host rocks. Geometry of deposits, structural, and geochemical features suggest that uranium minerals were deposited over a span of time from late Cretaceous to late Tertiary. Ore occurs in but is not offset by a shear zone that displaces mid-Tertiary rocks.. Economic zones of uranium are interpreted to have been secondarily enriched in late Tertiary time by downward and lateral migration of uranium into permeable zones where deposition was influenced by ground water controls and minerals that could reduce or neutralize uranium-bearing solutions.
LANDSAT-I (ERTS-I) multispectral reflectance data were used to enhance the detection of alteration around uranium deposits near Cameron, Ariz. The technique involved stretching and ratioing computer-enhanced data from which electronic noise and atmospheric haze had been removed. Using present techniques, the work proves that LANDSAT-I data are useful in detecting alteration around uranium deposits, but the method may still be improved. Bluish-gray mudstone in the target area could not be differentiated from the altered zones on the ratioed images. Further experiments involving combinations of ratioed and nonratioed data will be required to uniquely define the altered zones.
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