Capture zones for simple aquifers
Carl D. McElwee
1991, Ground Water (29) 587-590
Abstract. The protection and cleanup of aquifers is a matter of high priority for all states and the federal government. One concept that is receiving increased attention is that of wellhead protection. Capture zones showing the area influenced by a well within a certain time are...
Moment-tensor solutions estimated using optimal filter theory: global seismicity, 1988-1989
S.A. Sipkin, R.E. Needham
1991, Physics of the Earth and Planetary Interiors (67) 221-230
Moment-tensor solutions, estimated using optimal filter theory, are listed for 201 moderate-to-large earthquakes occurring from 1988 to 1989. ?? 1991....
Imaging the Juan de Fuca plate beneath southern Oregon using teleseismic P wave residuals
R.A. Harris, H. M. Iyer, P.B. Dawson
1991, Journal of Geophysical Research (96) 19879-19889
The Juan de Fuca plate subducts under the western margin of the North American plate in southern British Columbia, Washington, Oregon, and northern California. Benioff zone seismicity delineates shallow parts of the plate in Washington and northern California, whereas in Oregon there is a lack of...
Geochemical transformations and modeling of two deep-well injected hazardous wastes
William R. Roy, B. Seyler, J.D. Steele, S.C. Mravik, D.M. Moore, I.G. Krapac, J.M. Peden, R. A. Griffin
1991, Groundwater (29) 671-677
Two liquid hazardous wastes (an alkaline brine-like solution and a dilute acidic waste) were mixed with finely ground rock samples of three injection-related lithologies (sandstone, dolomite, and siltstone) for 155 to 230 days at 325°K-10.8 MPa. The pH and inorganic chemical composition of the alkaline waste were not significantly altered...
Neogene biostratigraphy and paleoenvironments of Enewetak Atoll, equatorial Pacific Ocean
T. M. Cronin, L.M. Bybell, E. M. Brouwers, T. G. Gibson, R. Margerum, R.Z. Poore
1991, Marine Micropaleontology (18) 101-114
Micropaleontologic analyses of Neogene sediments from Enewetak Atoll, Marshall Islands, provide data on the age of lagoonal deposits, stratigraphic disconformities and the paleoenvironmental and subsidence history of the atoll. Benthic foraminifers, planktic foraminifers, calcareous nannofossils and ostracodes were studied from six boreholes, the deepest penetrating 1605 feet below the lagoon...
Modern sedimentary environments in Boston Harbor, Massachusetts
H.J. Knebel, R.R. Rendigs, Michael H. Bothner
1991, Journal of Sedimentary Petrology (61) 791-804
Analyses of sidescan-sonar records supplemented by available bathymetric, sedimentary, subbottom, and bottom-current data reveal the distributions of the following three categories of sedimentary environments within the glaciated, topographically complex Boston Harbor estuary in Massachusetts. 1) Environments of erosion appear on the sonographs either as patterns with isolated strong reflections or...
Rates of soil development from four soil chronosequences in the southern Great Basin
J.W. Harden, E. M. Taylor, C. Hill, R. K. Mark, L. D. McFadden, M.C. Reheis, J.M. Sowers, S. G. Wells
1991, Quaternary Research (35) 383-399
Four soil chronosequences in the southern Great Basin were examined in order to study and quantify soil development during the Quaternary. Soils of all four areas are developed in gravelly alluvial fans in semiarid climates with 8 to 40 cm mean annual precipitation. Lithologies of alluvium are granite-gneiss at Silver...
Soil chronosequence studies in temperate to subtropical, low-latitude, low-relief terrain with data from the eastern United States
H. W. Markewich, M.J. Pavich
1991, Geoderma (51) 213-239
The Coastal Plain of the eastern United States is a low-latitude, low-altitude, low-relief terrain composed primarily of gently dipping marine and marginal-marine sediments that range in age from Cretaceous to Quaternary. Population density of the area is moderate, and most of the population is concentrated along the coast. Inland of...
Exploration drilling and reservoir model of the Platanares geothermal system, Honduras, Central America
F. Goff, S.J. Goff, S. Kelkar, L. Shevenell, A.H. Truesdell, J. Musgrave, H. Rufenacht, W. Flores
1991, Journal of Volcanology and Geothermal Research (45) 101-123
Results of drilling, logging, and testing of three exploration core holes, combined with results of geologic and hydrogeochemical investigations, have been used to present a reservoir model of the Platanares geothermal system, Honduras. Geothermal fluids circulate at depths ??? 1.5 km in a region of active tectonism devoid of Quaternary...
On plate tectonics and the geologic evolution of southwestern North America
P.L. Ward
1991, Journal of Geophysical Research (96) 12479-12496
Very rapid subduction of the Farallon plate under southwestern North America between 60 and 40 Ma was accompanied by a relatively low volume of magmatism throughout the southwestern United States and northern Mexico. Between 40 and 20 Ma, when subduction slowed significantly and in one...
Oil-generating coals of the San Juan Basin, New Mexico and Colorado, U.S.A.
J.L. Clayton, D. D. Rice, G.E. Michael
1991, Organic Geochemistry (17) 735-742
Coal beds of the Upper Cretaceous Fruitland Formation in the San Juan Basin of northwestern New Mexico and southwestern Colorado have significant liquid hydrocarbon generation potential as indicated by typical Rock-Eval Hydrogen Indexes in the range of 200–400 mg hydrocarbon/g organic carbon (type II and III organic matter). Small, non-commercial...
40Ar/39Ar systematics and argon diffusion in amber: Implications for ancient earth atmospheres
G. P. Landis, L.W. Snee
1991, Global and Planetary Change (5) 63-67
Argon isotope data indicate retained argon in bulk amber (matrix gas) is radiogenic [40Ar/39Ar ≃32o] than the much more abundant surface absorbed argon [40Ar/39Ar ≃295.5]. Neutron-induced 39Ar is retained in amber during heating experiments to 150° -250°C, with no evidence of recoiled 39Ar found after irradiation. A maximum permissible volume diffusion coefficient...
An AEM-TEM study of weathering and diagenesis, Abert Lake, Oregon: II. Diagenetic modification of the sedimentary assemblage
J.F. Banfield, B.F. Jones, D.R. Veblen
1991, Geochimica et Cosmochimica Acta (55) 2795-2810
This paper compares the mineralogy and chemistry of clay minerals in sediments from various depths and positions in Abert Lake and surrounding playa with those of the weathered materials entering the lake in order to reveal the nature and extent of post-depositional mineralogical modification.Analytical electron microscope (AEM) data from individual...
Origin of xenoliths in the trachyte at Puu Waawaa, Hualalai Volcano, Hawaii
David A. Clague, Wendy A. Bohrson
1991, Contributions to Mineralogy and Petrology (108) 439-452
Rare dunite and 2-pyroxene gabbro xenoliths occur in banded trachyte at Puu Waawaa on Hualalai Volcano, Hawaii. Mineral compositions suggest that these xenoliths formed as cumulates of tholeiitic basalt at shallow depth in a subcaldera magma reservoir. Subsequently, the minerals in the xenoliths underwent subsolidus reequilibration that particularly affected chromite...
A FORTRAN program for interpretation of relative permeability from unsteady-state displacements with capillary pressure included
E.O. Udegbunam
1991, Computers & Geosciences (17) 1351-1357
This paper presents a FORTRAN program for the determination of two-phase relative permeabilities from unsteady-state displacement data with capillary pressure terms included. The interpretative model employed in this program combines the simultaneous solution of a variant of the fractional flow equation which includes a capillary pressure term and an integro-differential...
Possible tectonomagnetic effect observed from mid-1989, to mid-1990, in Long Valley Caldera, California
R.J. Mueller, M.J.S. Johnston, J. O. Langbein
1991, Geophysical Research Letters (18) 601-604
Precise measurements of local magnetic fields have been obtained with a differentially connected array of three proton magnetometers in the Long Valley caldera region since 1984. Two magnetometers are located inside the caldera with a third reference magnetometer located 26km southeast of the caldera. After correction...
Densities of liquids and vapors in boiling NaCl-H2O solutions: a PVTx summary from 300° to 500°C
James L. Bischoff
1991, American Journal of Science (291) 309-338
Experimental data for densities of liquids and vapors on the two-phase surface of the system NaCl-H2O were compiled and evaluated to provide a complete summary between 300° and 500°C. The results are added to a previously published PTx summary compiled in the same manner to provide a PVTx summary of...
Flexural extension of the upper continental crust in collisional foredeeps
D. C. Bradley, W.S.F. Kidd
1991, Geological Society of America Bulletin (103) 1416-1438
Normal faults on the outer slopes of trenches and collisional foredeeps reveal that high-amplitude lithospheric flexure can result in inelastic extensional deformation of the convex side of a flexed plate. This process, which we call "flexural extension," differs fundamentally from rifting in that...
Thermodynamic assessment of hydrothermal alkali feldspar-mica-aluminosilicate equilibria
D.A. Sverjensky, J.J. Hemley, W. M. d’Angelo
1991, Geochimica et Cosmochimica Acta (55) 989-1004
The thermodynamic properties of minerals retrieved from consideration of solid-solid and dehydration equilibria with calorimetric reference values, and those of aqueous species derived from studies of electrolytes, are not consistent with experimentally measured high-temperature solubilities in the systems K2O- and Na2O-Al2O3-SiO2-H2O-HCl (e.g., K-fs — Ms — Qtz — K+ — H+)....
Proposed U.S. Geological Survey standard for digital orthophotos
David Hooper, Vincent Caruso
1991, Conference Paper, GIS/LIS 1991 ACSM-ASPRS Fall Convention
The U.S. Geological Survey has added the new category of digital orthophotos to the National Digital Cartographic Data Base. This differentially rectified digital image product enables users to take advantage of the properties of current photoimagery as a source of geographic information. The product and accompanying standard were implemented in...
Calibration of a texture-based model of a ground-water flow system, western San Joaquin Valley, California
Steven P. Phillips, Kenneth Belitz
1991, Ground Water (29) 702-715
The occurrence of selenium in agricultural drain water from the western San Joaquin Valley, California, has focused concern on the semiconfined ground-water flow system, which is underlain by the Corcoran Clay Member of the Tulare Formation. A two-step procedure is used to calibrate a preliminary model of the system for...
Statistical analyses of soil properties on a quaternary terrace sequence in the upper sava river valley, Slovenia, Yugoslavia
N. Vidic, M. Pavich, F. Lobnik
1991, Geoderma (51) 189-211
Alpine glaciations, climatic changes and tectonic movements have created a Quaternary sequence of gravely carbonate sediments in the upper Sava River Valley, Slovenia, Yugoslavia. The names for terraces, assigned in this model, Günz, Mindel, Riss and Würm in order of decreasing age, are used as morphostratigraphic terms. Soil chronosequence on...
Superposed deposits of thick coal on the eastern edge of the Illinois Basin and their association with underlying geologic features
D. Harper, G.A. Olyphant
1991, International Journal of Coal Geology (17) 273-296
Comparison of maps produced from publicly available data (drillers' logs, electrical logs and mine maps) provides a basis for inferring a deep-seated influence on the distribution of superposed deposits of thick coal (>1.4 m) in four Middle Pennsylvania (Desmoinesian Series) coal...
The effect of scale on the interpretation of geochemical anomalies
P. K. Theobald, R. G. Eppinger, R. L. Turner, S. Shiquan
1991, Journal of Geochemical Exploration (40) 9-23
The purpose of geochemical surveys changes with scale. Regional surveys identify areas where mineral deposits are most likely to occur, whereas intermediate surveys identify and prioritize specific targets. At detailed scales specific deposit models may be applied and deposits delineated.The interpretation of regional geochemical surveys must take into account scale-dependent...
Modeling the reflectance spectrum of Callisto 0.25 to 4.1μm
Wendy M. Calvin, Roger N. Clark
1991, Icarus (89) 305-317
The reflectance spectrum of Callisto from 0.2 to 4.1 μm is modeled using a simultaneous intimate plus areal mixture solution of ice and dark material which satisfies absorption band depths and reflectance levels. The model uses the radiative transfer theory based on Hapke's (1981, J. Geophys. Res. 86, 3039–3054) work, optical constants...
