Molecular orbital (SCF-Xα-SW) theory of metal-metal charge transfer processes in minerals - II. Application to Fe2+ --> Ti4+ charge transfer transitions in oxides and silicates
David M. Sherman
1987, Physics and Chemistry of Minerals (14) 364-367
A molecular orbital description, based on Xα-Scattered wave calculations on a (FeTiO10)14− cluster, is given for Fe2+ → Ti4+ charge transfer transitions in minerals. The calculated energy for the lowest Fe2+ → Ti4+ metal-metal charge transfer transition is 18040 cm−1 in reasonable agreement with energies observed in the optical spectra of Fe-Ti oxides and silicates. As...
Size and maceral association of pyrite in Illinois coals and their float-sink fractions
R.D. Harvey, P.J. DeMaris
1987, Organic Geochemistry (11) 343-349
The amount of pyrite (FeS2) removed by physical cleaning varies with differences in the amount of pyrite enclosed within minerals and of free pyrite in feed coals. A microscopic procedure for characterizing the size and maceral association of pyrite grains was developed and evaluate by testing three coals and their...
Testing the consistency for mapping urban vegetation with high-altitude aerial photographs and landsat MSS data
Franklin G. Sadowski, James A. Sturdevant, Rowan A. Rowntree
1987, Remote Sensing of Environment (21) 129-141
Two methods of analysis were evaluated for mapping urban vegetation on high-altitude, color-infrared aerial photographs and Landsat MSS data of Syracuse, NY. The first method consisted of defining the spatial patterns (strata) of urban vegetation occurrence. The second method discriminated woody and herbaceous vegetation classes within defined strata. Emphasis was...
CHANGES IN GRADE, VOLUME AND CONTAINED GOLD DURING THE MINING LIFE-CYCLE OF GOLD PLACER DEPOSITS.
J. D. Bliss, G. J. Orris, W. D. Menzie
1987, CIM Bulletin (80) 75-80
Analysis of gold placer data throughout the world suggests that gold grades and volumes cannot be used to distinguish between most types of gold placers. Only the alluvial plain and fan placers are significantly different among the types of gold placers considered. Gold grades and volumes change when working placers...
On predicting changes in the geomagnetic field
L.R. Alldredge
1987, Journal of Geophysical Research Solid Earth (92) 6331-6338
The present method of using constant secular variation rates to forecast magnetic components at a given site or to forecast spherical harmonic coefficients is known to be inaccurate. A new predictive method using trend and trigonometric functions fitted to known past values is used to extrapolate for a few years...
Coal deposits of the United States
Nelson W. John
1987, International Journal of Coal Geology (8) 355-365
The coal fields of the Unites States can be divided into six major provinces. The Appalachian and Interior Provinces contain dominantly bituminous coal in strata of Pennsylvanian age. The coal seams are relatively thin and are mined both by surface and...
Earlier sediment differential compaction in Gibson County, Indiana
Donald L. Eggert
1987, International Journal of Coal Geology (8) 305-314
A thick wedge of nonmarine gray shale extends from the Galatia Channel and overlies the Springfield Coal Member of the Petersburg Formation (Pennsylvania) in western Gibson Country, but mainly marine black shales overlie the Springfield in the eastern part of the...
Modeling and analysis of direct-current electrical resistivity in the Durham Triassic basin, North Carolina
C. Erwin Brown
1987, Geoexploration (24) 429-440
Sixty-two Schlumberger electrical soundings were made in the Durham Triassic basin in an effort to determine basin structural geometry, depth of the sedimentary layers, and spatial distribution of individual rock facies. A digital computer program was used to invert the sounding curves of apparent resistivity versus distance to apparent resistivity...
Global petrologic variations on the moon: A ternary-diagram approach.
P. A. Davis, P. D. Spudis
1987, Journal of Geophysical Research Solid Earth (92) 387-395
A ternary-diagram approach for determination of global petrologic variations on the lunar surface is presented that incorporates valuable improvements in our previous method of using geochemical variation diagrams. This new approach uses a ternary diagram that is subdivided into equally spaced segments along each of its three sides and has...
CALCULATION OF NONLINEAR CONFIDENCE AND PREDICTION INTERVALS FOR GROUND-WATER FLOW MODELS.
Richard L. Cooley, Aldo V. Vecchia
1987, Water Resources Bulletin (23) 581-599
A method is derived to efficiently compute nonlinear confidence and prediction intervals on any function of parameters derived as output from a mathematical model of a physical system. The method is applied to the problem of obtaining confidence and prediction intervals for manually-calibrated ground-water flow models. To obtain confidence and...
Transport of reacting solutes subject to a moving dissolution boundary: Numerical methods and solutions
Catherine Willis, Jacob Rubin
1987, Water Resources Research (23) 1561-1574
A moving boundary problem which arises during transport with precipitation-dissolution reactions is solved by three different numerical methods. Two of these methods (one explicit and one implicit) are based on an integral formulation of mass balance and lead to an approximation of a weak solution. These methods are compared to...
Coastal lava flows from Mauna Loa and Hualalai volcanoes, Kona, Hawaii
James G. Moore, D. Clague
1987, Bulletin of Volcanology (49) 752-764
A major carbonate reef which drowned 13 ka is now submerged 150 m below sea level on the west coast of the island of Hawaii. A 25-km span of this reef was investigated using the submersible Makali'i. The reef occurs on the flanks of two active volcanoes, Mauna Loa and...
Effects of weathering on biological marker and aromatic hydrocarbon composition of organic matter in Phosphoria shale outcrop
J.L. Clayton, J. D. King
1987, Geochimica et Cosmochimica Acta (51) 2153-2157
GC-MS analyses were performed on core samples collected from a shale outcrop of the Permian Phosphoria Formation in Utah, U.S.A., to study effects of weathering on selected biological marker and aromatic (phenanthrene) hydrocarbon compounds. Among the biological markers, the most important weathering effects are a decrease in the <span id="MathJax-Element-1-Frame"...
Evaluation of the stability of gas hydrates in Northern Alaska
A. Kamath, S. P. Godbole, R. D. Ostermann, T. S. Collett
1987, Cold Regions Science and Technology (14) 107-119
The factors which control the distribution of in situ gas hydrate deposits in colder regions such as Northern Alaska include; mean annual surface temperatures (MAST), geothermal gradients above and below the base of permafrost, subsurface pressures, gas composition, pore-fluid salinity and the soil condition. Currently existing data on the above...
Heat capacity and thermodynamic properties of andradite garnet, Ca3Fe2Si3O12, between 10 and 1000 K and revised values for ΔfGom (298.15 K) of hedenbergite and wollastonite
Richard A. Robie, Zhao Bin, Bruce S. Hemingway, Mark D. Barton
1987, Geochimica et Cosmochimica Acta (51) 2219-2224
The heat capacity of synthetic andradite garnet (Ca3Fe2Si3O12) was measured between 9.6 and 365.5 K by cryogenic adiabatic calorimetry and from 340 to 990 K by differential scanning calorimetry. At 298.15 KCop,m and Som are 351.9 ± 0.7 and 316.4 ± 2.0 J/(mol·K), respectively. Andradite has a λ-peak in Cop,m with a maximum at...
Compositional evidence regarding the origins of rims on Semarkona chondrules
J. N. Grossman, J. T. Wasson
1987, Geochimica et Cosmochimica Acta (51) 3003-3011
The compositions of the interiors and abraded surfaces of 7 chondrules from Semarkona (LL3.0) were measured by neutron activation analysis. For nonvolatile elements, the lithophile and siderophile element abundance patterns in the surfaces are generally similar to those in the corresponding interiors. Siderophile and chalcophile concentrations are much higher in...
Effects of substrate disturbance on secondary plant succession; Mojave Desert, California.
D.V. Prose, S.K. Metzger, H. G. Wilshire
1987, Journal of Applied Ecology (24) 305-313
(1) The effects of substrate disturbance on perennial plant succession in the Mojave Desert were assessed at three military camps abandoned for 40 years. (2) Soil compaction, removal of the top layer of soil, and alteration of drainage channel density caused significant changes in perennial plant cover, density, and relative...
Rheology of the lithosphere: Selected topics
S. H. Kirby, A. K. Kronenberg
1987, Reviews of Geophysics (25) 1219-1244
We review recent results concerning the rheology of the lithosphere with special attention to the following topics: 1) the flexure of the oceanic lithosphere, 2) deformation of the continental lithosphere resulting from vertical surface loads and forces applied at plate margins, 3) the rheological stratification of the continents, 4) strain...
Field observations of slush ice generated during freeze-up in arctic coastal waters
E. Reimnitz, E. W. Kempema
1987, Marine Geology (77) 219-231
In some years, large volumes of slush ice charged with sediment are generated from frazil crystals in the shallow Beaufort Sea during strong storms at the time of freeze-up. Such events terminate the navigation season, and because of accompanying hostile conditions,...
Lake Tapps tephra: An early Pleistocene stratigraphic marker in the Puget Lowland, Washington
J.A. Westgate, D. J. Easterbrook, N. D. Naeser, R. J. Carson
1987, Quaternary Research (28) 340-355
The rhyolitic Lake Tapps tephra was deposited about 1.0 myr ago, shortly after culmination of the early phase of the Salmon Springs Glaciation in the Puget Lowland. It is contained within sediments that were deposited in ponds or lakes in front of the reteating glacier. An herb-dominated tundra existed in...
Remote sensing investigations at a hazardous-waste landfill
Christopher Stohr, Wen-June Su, P.B. DuMontelle, R. A. Griffin
1987, Photogrammetric Engineering and Remote Sensing (53)
In 1976 state licensed landfilling of industrial chemicals was begun above an abandoned, underground coal mine in Illinois. Five years later organic chemical pollutants were discovered in a monitoring well, suggesting migration 100 to 1000 times faster than predicted by laboratory tests. Remote sensing contributed to the determination of the...
Biogeochemical cycling in an organic-rich coastal marine basin. 8. A sulfur isotopic budget balanced by differential diffusion across the sediment-water interface
J. P. Chanton, C.S. Martens, M. B. Goldhaber
1987, Geochimica et Cosmochimica Acta (51) 1201-1208
The sulfur isotopic composition of the sulfur fluxes occurring in the anoxic marine sediments of Cape Lookout Bight, N.C., U.S.A., was determined, and the result of isotopic mass balance was obtained via the differential diffusion model. Seasonal pore water sulfate δ34S measurements yielded a calculated sulfate input of 0.6%.. Sulfate transported into the sediments via diffusion...
The U.S. Midcontinent: a new frontier for mineral exploration.
W. P. Pratt, P.K. Sims
1987, Episodes (10) 303-307
The north-central US Midcontinent is underlain by a considerable thickness of sedimentary rocks, mostly Paleozoic, which lie upon a heterogeneous basement of Precambrian granitoid and metamorphic rocks. This article describes a representative sample of Midcontinent geology and explains why the authors believe this region is a 'new frontier' for mineral...
Recent geologic history of lake Atitlán, a caldera lake in western Guatemala
C. G. Newhall, C. K. Paull, J.P. Bradbury, A. Higuera-Gundy, L.J. Poppe, S. Self, Sharpless N. Bonar, J. Ziagos
1987, Journal of Volcanology and Geothermal Research (33) 81-107
Lake Atitlán, a caldera lake in western Guatemala, was investigated for evidence of recent volcanic and tectonic activity. No vents, faults, or folds are apparent on high-resolution seismic reflection profiles of lake sediment, representing at least 17,500 years and probably more than 35,000 years of deposition. Three post-caldera stratovolcanoes...
Theoretical analysis of the transient pressure response from a constant flow rate hydraulic conductivity test
Roger H. Morin, Harold W. Olsen
1987, Water Resources Research (23) 1461-1470
Incorporating a flow pump into a conventional triaxial laboratory system allows fluid to be supplied to or withdrawn from the base of a sediment sample at small and constant rates. An initial transient record of hydraulic head versus time is observed which eventually stabilizes to a constant steady state gradient...
