Seawater sulfate reduction and sulfur isotope fractionation in basaltic systems: interaction of seawater with fayalite and magnetite at 200–350°C
Wayne C. Shanks III, James L. Bischoff, Robert J. Rosenbauer
1981, Geochimica et Cosmochimica Acta (45) 1977-1995
Sulfate reduction during seawater reaction with fayalite and with magnetite was rapid at 350°C, producing equilibrium assemblages of talc-pyrite-hematite-magnetite at low water/rock ratios and talc-pyrite-hematite-anhydrite at higher water/rock ratios. At 250°C, seawater reacting with fayalite produced detectable amounts of dissolved H2S, but extent of reaction of solid phases was...
Storm-built sand ridges on the Maryland inner shelf: a preliminary report
D.J.P. Swift, M.E. Field
1981, Geo-Marine Letters (1) 33-37
Several aspects of the Maryland ridge field are pertinent to the problem of ridge genesis in response to Holocene sea-level rise. There is a systematic morphologic change from shoreface ridges through nearshore ridges to offshore ridges, which reflects the changing hydraulic regime. Grain size is 90?? out of phase with...
Economics and coal resource appraisal: strippable coal in the Illinois Basin ( USA)
E. D. Attanasi, E.K. Green
1981, Southern Economic Journal (47) 742-752
Coal-resource appraisals generally describe the location and general characteristics of coal beds. Estimates are made of the average overburden depth (depth of the coal bed below the surface), bed thickness, and perhaps certain chemical properties of the coal [1]. Although such resource compilations represent an important initial step, neither they...
Magnetic signals from the core of the earth and secular variation
L.R. Alldredge
1981, Journal of Geophysical Research Solid Earth (86) 7957-7965
An oscillating, radial magnetic dipole source was assumed to exist in the core of the earth, 100 km beneath the core-mantle boundary. As an approximation, electromagnetic propagation was assumed in the core in lieu of hydromagnetic propagation, which could not be used because of unknown internal fields.Using Debye potentials, the...
Correlation of natural gas content to iron species in the New Albany shale group
R.H. Shiley, R.M. Cluff, D. R. Dickerson, C.C. Hinckley, Gerard V. Smith, H. Twardowska, Mykola Saporoschenko
1981, Fuel (60) 732-738
Mössbauer parameters were obtained for four Illinois Basin shales and their corresponding < 2μm clay fractions from wells drilled through the New Albany Shale Group in Henderson, Tazewell, and Effingham counties in Illinois and Christian County in Kentucky. Off-gas analysis indicated that the Illinois cores were in an area of...
Earthquakes, March-April 1981
W. J. Person
1981, Earthquake Information Bulletin (USGS) (13) 195-198
There was on major earthquake (7.0-7.9) during this reporting period on April 24 in the Vanuatu Islands (formerly the New Hebrides islands). the series of strong earthquakes continued in Greece and caused additional casualties and damage, and Peru expereinced a moderate earthquake that caused fatalities and damage on April 18. In...
Sm-Nd systematics of a tonalitic augen gneiss and its constituent minerals from northern Michigan
K. Futa
1981, Geochimica et Cosmochimica Acta (45) 1245-1249
The Sm-Nd isotopic system of a tonalitic augen gneiss and its constituent minerals from northern Michigan was disturbed during metamorphism. Sm-Nd zircon ages are lower than the wholerock Sm-Nd model age. However, closely associated pairs of minerals (for example, sphene and biotite or apatite and plagioclase) retain their apparent metamorphic...
The origin and isotopic composition of dissolved sulfide in groundwater from carbonate aquifers in Florida and Texas
R. O. Rye, W. Back, B.B. Hanshaw, C.T. Rightmire, F. J. Pearson Jr.
1981, Geochimica et Cosmochimica Acta (45) 1941-1950
The δ34S values of dissolved sulfide and the sulfur isotope fractionations between dissolved sulfide and sulfate species in Floridan ground water generally correlate with dissolved sulfate concentrations which are related to flow patterns and residence time within the aquifer. The dissolved sulfide derives from the slow in situ biogenic reduction of sulfate dissolved from...
Matrix modification with silver for the electrothermal atomization of arsenic and selenium
R. F. Sanzolone, T. T. Chao
1981, Analytica Chimica Acta (128) 225-227
Silver as a matrix modifier is shown to improve the carbon-rod atomization of both arsenic and selenium for atomic absorption spectrometry. Compared to nickel, the efficiency of silver is greater for arsenic and about the same for selenium. Silver fulfils two functions in its reaction, namely stabilization during the ashing...
Cretaceous Arctic silicoflagellates
D. Bukry
1981, Geo-Marine Letters (1) 57-63
Cretaceous silicoflagellate assemblages from Arctic Ocean USGS Core 437 show Vallacerta siderea the most abundant species; most species of Lyramula disappear halfway up the core; only L. burchardae, n. sp., persists into the upper sections. These occurrences are untypical of the few documented Cretaceous assemblages from other areas. A Campanian...
Geodetic strain measurements in Washington
J.C. Savage, M. Lisowski, W.H. Prescott
1981, Journal of Geophysical Research Solid Earth (86) 4929-4940
Two new geodetic measurements of strain accumulation in the state of Washington for the interval 1972–1979 are reported. Near Seattle the average principal strain rates are 0.07 ± 0.03 μstrain/yr N 19°W and −0.13 ± 0.02 μstrain/yr N71°E, and near Richland (south central Washington) the average principal strain rates are...
Simulation model of Skeletonema costatum population dynamics in northern San Francisco Bay, California
J. E. Cloern, R. T. Cheng
1981, Estuarine, Coastal and Shelf Science (12) 83-100
A pseudo-two-dimensional model is developed to simulate population dynamics of one dominant phytoplankton species (Skeletonema costatum) in northern San Francisco Bay. The model is formulated around a conceptualization of this estuary as two distinct but coupled subsystems—a deep (10–20 m)...
13C 12C exchange between calcite and graphite: A possible thermometer in Grenville marbles
J.W. Valley, J. R. O’Neil
1981, Geochimica et Cosmochimica Acta (45) 411-419
The fractionation of 13C between calcite and graphite, Δ(Cc-Gr). is consistently small (2.6–4.8 permil) in 34 assemblages from upper amphibolite- and granulite-facies marbles of the Grenville Province. In 25 samples from the Adirondack Mountains, New York, it decreases regularly with increasing metamorphic temperature. The fractionations are independent of absolute δ13C values...
The Redskin granite: Evidence for thermogravitational diffusion in a Precambrian granite batholith
S. Ludington
1981, Journal of Geophysical Research Solid Earth (86) 10423-10430
The 1000-Ma-old composite Pikes Peak batholith consists largely of medium- to coarse-grained biotite granite but is intruded by several smaller granite plutons. Two of these, the Tarryall Mountains batholith and the Redskin Granite (Hawley, 1969; Hawley and Wobus, 1977), are here interpreted as cupolas atop the main mass of the...
Chrysophyte cysts as potential environmental indicators
D.P. Adam, A.D. Mahood
1981, Geological Society of America Bulletin (92) 839-844
Many Chrysophyte algae produce morphologically distinctive, siliceous, microscopic cysts during a resting stage of their life cycles; these cysts are often preserved in sediments. Scanning electron microscopy and Nomarski optics permit much more detailed observation of these cysts than was heretofore possible. We...
Satellite and field studies of man's impact on the surface in arid regions
Joseph Otterman
1981, Tellus, Series A: Dynamic Meteorology and Oceanography (33) 68-77
Models of the nadir reflectivity as a function of the fractional cover by plants or plant debris are presented and are applied to assessing the Negev vs Sinai differences and the sharp recovery (darkening) of the surface in a Sinai enclosure where anthropogenic pressures were stopped in 1974 by fencing...
A transient laboratory method for determining the hydraulic properties of 'tight' rocks-I. Theory
P. A. Hsieh, J.V. Tracy, C. E. Neuzil, J.D. Bredehoeft, Stephen E. Silliman
1981, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts (18) 245-252
Transient pulse testing has been employed increasingly in the laboratory to measure the hydraulic properties of rock samples with low permeability. Several investigators have proposed a mathematical model in terms of an initial-boundary value problem to describe fluid flow in a transient pulse test. However, the solution of this problem...
Strain accumulation across the Denali fault in the Delta River canyon, Alaska
J.C. Savage, M. Lisowski, W.H. Prescott
1981, Journal of Geophysical Research Solid Earth (86) 1005-1014
Deformation along the Denali fault in the Delta River canyon was determined from geodetic surveys in 1941/1942, 1970, 1975, and 1979. The data were best for the 1975–1979 interval; in that period the average strain accumulation was essentially pure right lateral shear at a rate of 0.6 ± 0.1 μrad/a...
Chemistry of rock-forming minerals of the Cretaceous-Paleocene batholith in southwestern Japan and implications for magma genesis
G.K. Czamanske, S. Ishihara, S.A. Atkin
1981, Journal of Geophysical Research Solid Earth (86) 10431-10469
Petrographic descriptions and electron microprobe analyses of minerals are presented for 35 specimens from seven suites chosen to examine the transition from magnetite series to ilmenite series granitoids along two transects across the Cretaceous-Paleocene Inner Zone batholith of southwestern Japan. Regularities in chemical compositions of amphiboles, biotites, and feldspars suggest...
Significant results from using earth observation satellites for mineral and energy resource exploration
William D. Carter
1981, Advances in Space Research (1) 261-269
A large number of Earth-observation satellites orbit our world several times each day, providing new information about the land and sea surfaces and the overlying thin layer of atmosphere that makes our planet unique. Meteorological satellites have had the longest history of experimental use and most are now considered operational....
Crystal growth of calcite from calcium bicarbonate solutions at constant PCO2 and 25°C: a test of a calcite dissolution model
Michael M. Reddy, Niel Plummer, E. Busenberg
1981, Geochimica et Cosmochimica Acta (45) 1281-1289
A highly reproducible seeded growth technique was used to study calcite crystallization from calcium bicarbonate solutions at 25°C and fixed carbon dioxide partial pressures between 0.03 and 0.3 atm. The results are not consistent with empirical crystallization models that have successfully described calcite growth at low PCO2 (< 10−3 atm). Good agreement was...
Design of exploration and minerals-data-collection programs in developing areas
E. D. Attanasi
1981, Socio-Economic Planning Sciences (15) 347-352
This paper considers the practical problem of applying economic analysis to designing minerals exploration and data collection strategies for developing countries. Formal decision rules for the design of government exploration and minerals-data-collection programs are derived by using a minerals-industry planning model that has been extended to include an exploration function....
Multiple-element semiquantitative analysis of one-milligram geochemical samples by D.C. arc emission spectrography
N. Rait
1981, Chemical Geology (32) 317-333
A modified method is described for a 1-mg sample multi-element semiquantitative spectrographic analysis. This method uses a direct-current arc source, carbon instead of graphite electrodes, and an 80% argon-20% oxygen atmosphere instead of air. Although this is a destructive method, an analysis can be made for 68 elements in all...
Petrology and geochronology of metamorphosed volcanic rocks and a middle Cretaceous volcanic neck in the east-central Sierra Nevada, California
R. W. Kistler, S.E. Swanson
1981, Journal of Geophysical Research Solid Earth (86) 10489-10501
Metamorphosed Mesozoic volcanic rocks from the east-central Sierra Nevada range in composition from basalt to rhyolite and have ages, based on whole rock Rb-Sr and U-Pb zircon dating, of about 237–224, 185, 163, 134, and 100 m.y. The major plutons of the batholith in this area are of Triassic (215–200...
Simulative models for the analysis of ground-water flow in Vekol Valley, the Waterman Wash area, and the Bosque area, Maricopa and Pina Counties, Arizona
D. T. Matlock
1981, Open-File Report 82-77
Simulative ground-water flow models for Vekol Valley, the Waterman Wash area, and the Bosque area were developed for use in evaluating alternatives for developing a ground-water supply for the Ak-Chin Indian Community. The hydraulic properties of the basin-fill deposits used in the models were estimated primarily from aquifer tests made...
