Seismicity and shear strain in the southern Great Basin of Nevada and California
J. Gomberg
1991, Journal of Geophysical Research (96) 16383-16399
This study examines the relationship between the distribution of small earthquakes (ML≤4.3) and mechanisms of strain accumulation and relaxation in an area with long repeat times between large events, the Southern Great Basin Seismic Network (SGBSN) region. The Great Basin is a unique continental extensional...
A geochemical model of the Platanares geothermal system, Honduras
C. J. Janik, A.H. Truesdell, F. Goff, L. Shevenell, M.L. Stallard, P.E. Trujillo Jr., D. Counce
1991, Journal of Volcanology and Geothermal Research (45) 125-146
Results of exploration drilling combined with results of geologic, geophysical, and hydrogeochemical investigations have been used to construct a geochemical model of the Platanares geothermal system, Honduras. Three coreholes were drilled, two of which produced fluids from fractured Miocene andesite and altered Cretaceous to Eocene conglomerate at 450 to 680...
Automated urban change detection using scanned cartographic and satellite image data
Jeffrey D. Spooner
1991, Conference Paper, GIS/LIS 1991 ACSM-ASPRS Fall Convention
The objective of this study was to develop a digital procedure to measure the amount of urban change that has occurred in an area since the publication of its corresponding 1:24,000-scale topographic map. Traditional change detection techniques are dependent upon the visual comparison of high-altitude aerial photographs or, more recently,...
A refinement of the combination equations for evaporation
P. C. D. Milly
1991, Surveys in Geophysics (12) 145-154
Most combination equations for evaporation rely on a linear expansion of the saturation vapor-pressure curve around the air temperature. Because the temperature at the surface may differ from this temperature by several degrees, and because the saturation vapor-pressure curve is nonlinear, this approximation leads to a certain degree of error...
Fluid inclusions and preliminary studies of hydrothermal alteration in core hole PLTG-1, Platanares geothermal area, Honduras
K.E. Bargar
1991, Journal of Volcanology and Geothermal Research (45) 147-160
The Platanares geothermal area in western Honduras consists of more than 100 hot springs that issue from numerous hot-spring groups along the banks or within the streambed of the Quebrada de Agua Caliente (brook of hot water). Evaluation of this geothermal area included drilling a 650-m deep PLTG-1 drill hole...
Numerical assessment of a landfill compliance limit
Bruce R. Hensel, Donald A. Keefer, Robert A. Griffin, Richard Berg
1991, Groundwater (29) 218-224
The PLASM and Random Walk ground-water flow and contaminant transport models were used to assess the potential impact of various proposed regulatory compliance distances on landfill siting. Contaminant transport modeling was performed for 16 generalized geological sequences representative of hydrogeological conditions over an estimated 90...
Mytiloides hattini n. sp.: a guide fossil for the base of the Turonian in the Western Interior of North America
W.P. Elder
1991, Journal of Paleontology (65) 234-241
Mytiloides hattini, a new species of inoceramid bivalve from the basal Turonian (Upper Cretaceous), is described and its stratigraphic importance discussed. This inoceramid is particularly significant because its first occurrence can be used as a marker for the base of the Turonian in strata that typically contain no ammonites and...
Characteristics of low-slope streams that affect O2 transfer rates
Gene W. Parker, Leslie A. DeSimone
1991, Conference Paper, Air-Water Mass Transfer
Multiple-regression techniques were used to derive the reaeration coefficients estimating equation for low sloped streams: K2 = 3.83 MBAS-0.41 SL0.20 H-0.76, where K2 is the reaeration coefficient in base e units per day; MBAS is the methylene blue active substances concentration in milligrams per liter; SL is the water-surface slope...
Ground-water recharge from streamflow data, NW Florida
John Vecchioli, W. C. Bridges, Roger P. Rumenik, J. W. Grubbs
1991, Conference Paper
Annual base flows of streams draining Okaloosa County and adjacent areas in northwest Florida were determined through hydrograph separation and correlation techniques for purposes of evaluating variations in ground-water recharge rates. Base flows were least in the northern part of the county and greatest in the southern part. Topographic and...
Jasper Seamount: Seven million years of volcanism
M. S. Pringle, H. Staudigel, J. Gee
1991, Geology (19) 364-368
Jasper Seamount is a young, mid-sized (690 km3) oceanic intraplate volcano located about 500 km west-southwest of San Diego, California. Reliable 40Ar/39Ar age data were obtained for several milligram-sized samples of 4 to 10 Ma plagioclase by using a defocused laser beam to clean...
A review of the regional geophysics of the Arizona Transition Zone
J. D. Hendricks, J. B. Plescia
1991, Journal of Geophysical Research (96) 12351-12373
A review of existing geophysical information and new data presented in this special section indicate that major changes in crustal properties between the Basin and Range and Colorado Plateau occur in, or directly adjacent to, the region defined as the Arizona Transition Zone. Although this region...
Real-time Seismic Amplitude Measurement (RSAM): a volcano monitoring and prediction tool
E.T. Endo, T. Murray
1991, Bulletin of Volcanology (53) 533-545
Seismicity is one of the most commonly monitored phenomena used to determine the state of a volcano and for the prediction of volcanic eruptions. Although several real-time earthquake-detection and data acquisition systems exist, few continuously measure seismic amplitude in circumstances where individual events are difficult to recognize or where volcanic...
Comparison of organic geochemistry and metal enrichment in two black shales: Cambrian Alum Shale of Sweden and Devonian Chattanooga Shale of United States
J.S. Leventhal
1991, Mineralium Deposita (26) 104-112
In most black shales, such as the Chattanooga Shale and related shales of the eastern interior United States, increased metal and metalloid contents are generally related to increased organic carbon content, decreased sedimentation rate, organic matter type, or position in the basin. In areas where the stratigraphic equivalents of the...
Geology and petrology of Mahukona Volcano, Hawaii
D.A. Clague, James G. Moore
1991, Bulletin of Volcanology (53) 159-172
The submarine Mahukona Volcano, west of the island of Hawaii, is located on the Loa loci line between Kahoolawe and Hualalai Volcanoes. The west rift zone ridge of the volcano extends across a drowned coral reef at about-1150 m and a major slope break at about-1340...
Conditions leading to a recent small hydrothermal explosion at Yellowstone National Park
R.O. Fournier, J. M. Thompson, C. G. Cunningham, R. A. Hutchinson
1991, Geological Society of America Bulletin (103) 1114-1120
Porkchop Geyser, in Yellowstone National Park, was the site of a small hydrothermal explosion on September 5, 1989. In the early 1960s, this was a quiescent spring with an intermittent seeping discharge. Infrequent geyser eruptions 3-5 m high started in 1971, and in 1985 the geyser began erupting as a...
Assessing the effects of microbial metabolism and metabolities on reservoir pore structure
E.O. Udegbunam, J.P. Adkins, R.M. Knapp, M.J. McInerney, R.S. Tanner
1991, Conference Paper, Proceedings - SPE Annual Technical Conference and Exhibition
The effect of microbial treatment on pore structure of sandstone and carbonatereservoirs was determined. Understanding how different bacterial strains and their metabolic bioproducts affect reservoir pore structure will permit the prudent application of microorganisms for enhanced oil recovery. The microbial strains tested included Clostridium acetobutylicum, a polymer-producing Bacillus strain, and...
Segmentation and the coseismic behavior of basin and range normal faults. Examples from east-central Idaho and southwestern Montana, USA
Anthony J. Crone, Kathleen M. Haller
1991, Journal of Structural Geology (13) 165-176
The range-front normal faults of the Lost River and Lemhi Ranges, and the Beaverhead and Tendoy Mountains in east-central Idaho and southwestern Montana have well-preserved fault scarps on Quaternary deposits along much of their lengths. Fault-scarp morphology, the age of deposits displaced by the faults, and the morphology of the...
The collision zone between the North d'Entrecasteaux Ridge and the New Hebrides island arc. 2. Structure from multichannel seismic data
M. A. Fisher, J.-Y. Collot, E.L. Geist
1991, Journal of Geophysical Research (96) 4479-4495
The d'Entrecasteaux zone (DEZ) collides with the central New Hebrides island arc and consists of two subparallel ridges that strike east-west, stand 1–2 km above the surrounding oceanic plate, and subduct obliquely (15°) northward beneath the arc. Rocks dredged from the north ridge as well...
Measuring the benefits of GIS use
Stephen R. Gillespie
1991, Conference Paper, GIS/LIS 1991 ACSM-ASPRS Fall Convention
The key to objectively measuring the benefits of GIS use is to realize that there are two different types of benefits and that different techniques must be used to measure each. Efficiency benefits occur when the same task previously done without the GIS can be done less expensively with the...
Radon-222 and its parent radionuclides in groundwater from two study areas in New Jersey and Maryland, U.S.A.
R. B. Wanty, S. L. Johnson, Paul H. Briggs
1991, Applied Geochemistry (6) 305-318
A study of groundwater chemistry and radionuclide mobility in New Jersey and Maryland was conducted to investigate natural processes that control the mobility of radionuclides in the water-rock system. Groundwater was sampled from two geological units in New Jersey and from six in Maryland. The water sampled was from aquifiers...
Release of 226Ra from uranium mill tailings by microbial Fe(III) reduction
E. R. Landa, Elizabeth J.P. Phillips, Derek R. Lovley
1991, Applied Geochemistry (6) 647-652
Uranium mill tailings were anaerobically incubated in the presence of H2 with Alteromonas putrefaciens, a bacterium known to couple the oxidation of H2 and organic compounds to the reduction of Fe(III) oxides. There was a direct correlation between the extent of Fe(III) reduction and...
Revised age of deglaciation of Lake Emma based on new radiocarbon and macrofossil analyses
S. A. Elias, P. E. Carrara, L.J. Toolin, A.J.T. Jull
1991, Quaternary Research (36) 307-321
Previous radiocarbon ages of detrital moss fragments in basal organic sediments of Lake Emma indicated that extensive deglaciation of the San Juan Mountains occurred prior to 14,900 yr B.P. (Carrara et al., 1984). Paleoecological analyses of insect and plant macrofossils from these basal sediments cast doubt on the reliability of...
The use of mineralogic techniques as relative age indicators for weathering profiles on the Atlantic Coastal Plain, USA
D. R. Soller, J. P. Owens
1991, Geoderma (51) 111-131
Textural, geochemical, and mineralogic study of soils and weathering profiles has led to the practice of applying varioys weathering parameters as relative age indicators. In our studies examined the entire thickness of weathered sediment (i.e., the weathering profile) for evidence of weathering-induced changes in both sand- and clay-sized mineralogy, and...
Examination of micrinite concentrates from the Cannel City coal bed of eastern Kentucky: Proposed mechanism of formation
D.N. Taulbee, J.C. Hower, S.F. Greb
1991, Organic Geochemistry (17) 557-565
A high volatile B, micrinite-rich bituminous coal from Morgan County, Kentucky, was crushed and screened to −100 mesh, demineralized and subjected to density gradient centrifugation (DGC). In an initial density separation, micrinite concentration was increased from 52 vol% in the demineralized coal to a maximum of 67% in the 1.25–1.26...
Field and modelling studies of immiscible fluid flow above a contaminated water-table aquifer
W.N. Herkelrath, H.I. Essaid, K.M. Hess
1991, Conference Paper, National Conference Publication - Institution of Engineers, Australia
A method was developed for measuring the spatial distribution of immiscible liquid contaminants in the subsurface. Fluid saturation distributions measured at a crude-oil spill site were used to test a numerical multiphase flow model....
