Jasperoid float and stream cobbles as tools in geochemical exploration for hydrothermal ore deposits
T.G. Lovering
1981, Journal of Geochemical Exploration (14) 69-81
Fragments of silicified rocks that are associated with deposits of base and precious metals may be transported as cobbles and pebbles in alluvium far downstream from the source outcrop. These rocks commonly exhibit certain characteristics which distinguish them from other detrital siliceous material, and may thus serve as a useful...
Adsorption of dissolved organics in lake water by aluminum oxide. Effect of molecular weight
J.A. Davis, R. Gloor
1981, Environmental Science & Technology (15) 1223-1229
No abstract available....
Seismic amplitude anomalies associated with thick First Leo sandstone lenses, eastern Powder River basin, Wyoming
A. H. Balch, Myung W. Lee, J. J. Miller, R. T. Ryder
1981, Geophysics (46) 1519-1527
Several new discoveries of oil production in the Leo sandstone, an economic unit in the Pennsylvanian middle member of the Minnelusa formation, eastern Powder River basin, Wyoming-Nebraska-South Dakota, have renewed exploration interest in this area. Vertical seismic profiles (VSP) and model studies suggested that a measurable seismic amplitude anomaly is...
Effects of erosion control structures along a portion of the northern Chesapeake Bay shoreline
C.F. Zabawa, R.T. Kerhin, S. Bayley
1981, Environmental Geology (3) 201-211
A 6.500-meter reach of western Chesapeake Bay shoreline (lower Mayo Peninsula) lost about 1.1??106 cubic meters of sediment (equivalent to 170 cubic meters lost per meter of shoreline) between 1846 and 1932, when the first aerial photographs show the shoreline already substantially protected by a system of groins and intermittent...
Rates of manganese oxidation in aqueous systems
J.D. Hem
1981, Geochimica et Cosmochimica Acta (45) 1369-1374
The rate of crystal growth of Mn3O4 (hausmannite) and βMnOOH (feitknechtite) in aerated aqueous manganous perchlorate systems, near 0.01 M in total manganese, was determined at pH levels ranging from 7.00 to 9.00 and at temperatures from 0.5 to 37.4°C. The process is autocatalytic, but becomes psuedo first-order in dissolved Mn2+ activity...
Fractionation of carbon and hydrogen isotopes by methane-oxidizing bacteria
D.D. Coleman, J.B. Risatti, M. Schoell
1981, Geochimica et Cosmochimica Acta (45) 1033-1037
Carbon isotopic analysis of methane has become a popular technique in the exploration for oil and gas because it can be used to differentiate between thermogenic and microbial gas and can sometimes be used for gas-source rock correlations. Methane-oxidizing bacteria, however,...
A review of regional mineral resource assessment methods
D.A. Singer, D.L. Mosier
1981, Economic Geology (76) 1006-1015
Over 100 papers on regional mineral resource assessment of nonfuels are classified according to method(s) used and form(s) of product in order to help identify possible methods for future assessments. Types of products that have been used include: tons of metal; tons of rock and associated grade; gross value; potential;...
Depositional sequences in clastic continental slope deposits, Gulf of Mexico
A.H. Bouma
1981, Geo-Marine Letters (1) 115-121
Tertiary and Quaternary sediments, overlying diapiric older Tertiary shales and Louann Salt on the continental slope in the western Gulf of Mexico, show cyclicity based on seismic-reflection patterns. A set of indistinct parallel reflections or an acoustically semi-transparent zone, normally onlapping onto diapir flanks, alternates with a set of distinct...
Molecular carbon isotopic evidence for the origin of geothermal hydrocarbons
D.J. Des Marais, J.H. Donchin, N.L. Nehring, A.H. Truesdell
1981, Nature (292) 826-828
Previous interest in light hydrocarbons from geothermal systems has focused principally on the origin of the methane1 and the estimation of subsurface temperatures from the carbon isotopic content of coexisting methane and carbon dioxide1-3. Higher molecular weight hydrocarbons were first reported in gases from Yellowstone National Park4, and have since...
Estimating usable resources from historical industry data
S.M. Cargill, D. H. Root, E. H. Bailey
1981, Economic Geology (76) 1081-1095
Historical production statistics are used to predict the quantity of remaining usable resources. The commodities considered are mercury, copper and its byproducts gold and silver, and petroleum; the production and discovery data are for the United States. The results of the study indicate that the cumulative return per unit of...
Anomalous chemical changes in well waters and possible relation to earthquakes
Chi-Yu King, William C. Evans, T. Presser, R.H. Husk
1981, Geophysical Research Letters (8) 425-428
Water level, temperature, salinity, electric conductivity, and pH have been measured periodically for several years at three water wells located along a 17-km segment of the San Andreas fault between San Juan Bautista and Cienega Winery in central California. Water samples were collected at the same...
Rank of coal beds of the Narragansett basin, Massachusetts and Rhode Island
P.C. Lyons, H.B. Chase Jr.
1981, International Journal of Coal Geology (1) 155-168
Coal of the Narragansett basin generally has been considered to be anthracite and/or meta-anthracite. However, no single reliable method has been used to distinguish these two ranks in this basin. Three methods — chemical, X-ray, and petrographic — have been used...
Effects of the atmosphere on the detection of surface changes from Landsat multispectral scanner data
Joseph Otterman, Charles J. Robinove
1981, International Journal of Remote Sensing (2) 351-360
The atmospheric effects on radiometric data recorded in the Landsat multispectral scanner system (MSS) bands are compiled for cases of representative and ideal atmospheric conditions. The effects are expressed as a difference between the Earth's surface spectral reflectivity, a0, and the surface-atmosphere system spectral reflectivity, as, derived from the satellite...
Determination of organic-matter content of Appalachian Devonian shales from gamma-ray logs
James W. Schmoker
1981, American Association of Petroleum Geologists Bulletin (65) 1285-1298
The organic-matter content of the Devonian shale of the Appalachian basin is important for assessing natural-gas resources. In most of the western part of the Appalachian basin the organic-matter content of the Devonian shale can be estimated from gamma-ray wire-line logs. Organic-matter contents estimated using these logs are compared with...
A transient laboratory method for determining the hydraulic properties of 'tight' rocks-II. Application
C. E. Neuzil, C. Cooley, Stephen E. Silliman, J.D. Bredehoeft, P. A. Hsieh
1981, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts (18) 253-258
In Part I a general analytical solution for the transient pulse test was presented. Part II presents a graphical method for analyzing data from a test to obtain the hydraulic properties of the sample. The general solution depends on both hydraulic conductivity and specific storage and, in theory, analysis of...
Geochemical evidence for modern sediment accumulation on the continental shelf off southern New England
Michael H. Bothner, E.C. Spiker, P. P. Johnson, R.R. Rendigs, P. J. Aruscavage
1981, Journal of Sedimentary Petrology (51) 281-292
An area of fine-grained sediment approximately 170 km x 74 km in size, located in water depths between 60 m and 150 m, south of Martha's Vineyard, Mass., is a site of modern sediment deposition. The 14C ages systematically increase with sediment depth from about 1,300 years B.P. at the...
The accommodation of relative motion at depth on the San Andreas fault system in California
W.H. Prescott, A. Nur
1981, Journal of Geophysical Research Solid Earth (86) 999-1004
Plate motion below the seismogenic layer along the San Andreas fault system in California is generally assumed to occur by aseismic slip along a deeper extension of the fault. It is also possible that below the seismogenic layer, deformation is distributed laterally over a zone. Several observed features of the...
Lu-Hf total-rock age for the Amîtsoq gneisses, West Greenland
H.S. Pettingill, P. J. Patchett
1981, Earth and Planetary Science Letters (55) 150-156
Lu-Hf total-rock data for the Amîtsoq gneisses of West Greenland yield an age of 3.55±0.22Gy(2σ), based on the decay constant λ176Lu=1.96×10−11y−1, and an initial176Hf/177Hf ratio of 0.280482±33. The result is in good agreement with Rb-Sr total-rock and U-Pb zircon ages. In spite of severe metamorphism of the area at 2.9...
Geology and geochemistry of gas-charged sediment on Kodiak Shelf, Alaska
M. A. Hampton, K.A. Kvenvolden
1981, Geo-Marine Letters (1) 141-147
Methane concentrations in some sediment cores from the Kodiak Shelf and adjacent continental slope increase with depth by three or four orders of magnitude and exceed the solubility in water at ambient conditions. Acoustic anomalies in seismic-reflection records imply that methane-rich sediment is widespread. Molecular composition of hydrocarbon gases and...
Experimental seawater-basalt interaction at 300°C, 500 bars, chemical exchange, secondary mineral formation and implications for the transport of heavy metals
W.E. Seyfried Jr., J. L. Bischoff
1981, Geochimica et Cosmochimica Acta (45) 135-147
Seawater and NaCl solutions were reacted with basalt (basalt glass and diabase) for several months at 300°C, 500 bars and a water/rock ratio of 10. During reaction, seawater was significantly modified, increasing in Ca, H2S, CO2. SiO2, K. Fe, Mn. Ba, Al and H+, and decreasing in Mg and...
A routine high-precision method for Lu-Hf isotope geochemistry and chronology
P. J. Patchett, M. Tatsumoto
1981, Contributions to Mineralogy and Petrology (75) 263-267
A method for chemical separation of Lu and Hf from rock, meteorite and mineral samples is described, together with a much improved mass spectrometric running technique for Hf. This allows (i) geo- and cosmochronology using the176Lu???176Hf+??- decay scheme, and (ii) geochemical studies of planetary processes in the earth and moon....
Mars and Earth: Comparison of cold-climate features
Baerbel K. Lucchitta
1981, Icarus (45) 264-303
On Earth, glacial and periglacial features are common in areas of cold climate. On Mars, the temperature of the present-day surface is appropriate for permafrost, and the presence of water is suspected from data relating to the outgassing of the planet, from remote-sensing measurements over the polar caps and elsewhere...
Application of capillary gas chromatography mass spectrometry/computer techniques to synoptic survey of organic material in bed sediment
Thomas R. Steinheimer, Wilfred E. Pereira, Sharon M. Johnson
1981, Analytica Chimica Acta (129) 57-67
A bed sediment sample taken from an area impacted by heavy industrial activity was analyzed for organic compounds of environmental significance. Extraction was effected on a Soxhlet apparatus using a freeze-dried sample. The Soxhlet extract was fractionated by silica gel micro-column adsorption chromatography. Separation and identification of the organic compounds...
Computer-assisted photogrammetric mapping systems for geologic studies-A progress report
C. L. Pillmore, K.S. Dueholm, H.S. Jepsen, C.H. Schuch
1981, Photogrammetria (36) 159-171
Photogrammetry has played an important role in geologic mapping for many years; however, only recently have attempts been made to automate mapping functions for geology. Computer-assisted photogrammetric mapping systems for geologic studies have been developed and are currently in use in offices of the Geological Survey of Greenland at Copenhagen,...
210Pb method for estimating the rate of carbonate sand sedimentation
Charles W. Holmes
1981, Geo-Marine Letters (1) 237-241
The plot of 210Pb activity against depth in carbonate sands on the Virgin Island Bank is a negative asymmetric hyperbolic curve. As depth increases, an initial rapid decrease in 210Pb activity caused by the decay of unsupported 210Pb and 226Ra is followed by increasing activity as a result of 210Pb...
