Seismic-wave attenuation associated with crustal faults in the New Madrid seismic zone
R. M. Hamilton, Walter D. Mooney
1990, Science (248) 351-354
The attenuation of upper crustal seismic waves that are refracted with a velocity of about 6 kilometers per second varies greatly among profiles in the area of the New Madrid seismic zone in the central Mississippi Valley. The waves that have the strongest attenuation pass through the seismic trend along...
Differentiator design and performance for edge sharpening
Jeng-Jong Pan, Julia O. Domingue
1990, Photogrammetric Engineering and Remote Sensing (56) 573-578
A two-dimensional differentiator is useful for edge sharpening in digital image processing. In the design of a differentiator, differentiator coefficients that satisfy the specification of frequency response must be approximated. Four mathematical techniques - the minimax method, least-squares method, nonlinear programming, and linear programming - can be applied to solve...
Deformation monitoring at Nevado del Ruiz, Colombia - October 1985 - March 1988
N.G. Banks, C. Carvajal, H. Mora, E. Tryggvason
1990, Journal of Volcanology and Geothermal Research (41) 269-295
Deformation studies began at Nevado del Ruiz 23 days before the devastating 13 November 1985 eruption, at least 12 months after precursory seismicity and fumarolic activity began. The late start in geodetic monitoring, limited number of stations in the pre-eruption network, and inconsistent patterns in the observed deformation limit conclusions...
Regionalization in geology by multivariate classification
Jan Harff, J.C. Davis
1990, Mathematical Geology (22) 573-588
The concept of multivariate classification of "geological objects" can be combined with the concept of regionalized variables to yield a procedure for typification of geological objects, such as rock units, well records, or samples. Numerical classification is followed by subdivision of the area of investigation, and culminates in a regionalization...
Hydrocarbon geochemistry of hydrothermally generated petroleum from Escanaba trough, offshore California U.S.A.
K.A. Kvenvolden, J. B. Rapp, F. D. Hostettler
1990, Applied Geochemistry (5) 83-91
In 1986, three samples of sulfide-rich sediments, impregnated with hydrothermally derived, asphaltic petroleum, were recovered in a dredge and by submersible from Escanaba Trough, the sediment-covered, southern end of the Gorda Ridge spreading axis, offshore northern California. The molecular distributions of...
Fast algorithm for automatically computing Strahler stream order
Kenneth J. Lanfear
1990, Water Resources Bulletin (26) 977-981
An efficient algorithm was developed to determine Strahler stream order for segments of stream networks represented in a Geographic Information System (GIS). The algorithm correctly assigns Strahler stream order in topologically complex situations such as braided streams and multiple drainage outlets. Execution time varies nearly linearly with the number of...
A comparison of two- and three-dimensional stochastic models of regional solute movement
A.M. Shapiro, V.D. Cvetkovic
1990, Transport in Porous Media (5) 1-25
Recent models of solute movement in porous media that are based on a stochastic description of the porous medium properties have been dedicated primarily to a three-dimensional interpretation of solute movement. In many practical problems, however, it is more convenient and consistent with measuring techniques to consider flow and solute...
Reaction paths and equilibrium end-points in solid-solution aqueous-solution systems
P. D. Glynn, E.J. Reardon, Niel Plummer, E. Busenberg
1990, Geochimica et Cosmochimica Acta (54) 267-282
Equations are presented describing equilibrium in binary solid-solution aqueous-solution (SSAS) systems after a dissolution, precipitation, or recrystallization process, as a function of the composition and relative proportion of the initial phases. Equilibrium phase diagrams incorporating the concept of stoichiometric saturation are used to interpret possible reaction paths and to demonstrate...
Constraints on the tectonics of the Mule Mountains thrust system, southeast California and southwest Arizona
R. M. Tosdal
1990, Journal of Geophysical Research Solid Earth (95) 20025-20048
The Mule Mountains thrust system crops out discontinuously over a 100-km-strike length in the Blythe-Quartzsite region of southeast California and southwest Arizona. Along the thrust system, middle and upper crustal metamorphic and plutonic rocks of Proterozoic and Mesozoic age are thrust north-northeastward (015° to 035°) over a lower plate metamorphic...
Shallow structure and deformation along the San Andreas Fault in Cholame Valley, California, based on high-resolution reflection profiling
K. M. Shedlock, T.M. Brocher, S.T. Harding
1990, Journal of Geophysical Research (95) 5003-5020
The mapped active traces of the San Andreas fault are separated by a 1-km-wide right-stepping offset in Cholame Valley. The geometry of this offset, defined in other strike-slip systems as a releasing bend or a dilational jog, has resulted in the formation of a pullapart basin. Various researchers have inferred...
Flexure and faulting of sedimentary host rocks during growth of igneous domes, Henry Mountains, Utah
M.D. Jackson, D. D. Pollard
1990, Journal of Structural Geology (12) 185-206
A sequence of sedimentary rocks about 4 km thick was bent, stretched and uplifted during the growth of three igneous domes in the southern Henry Mountains. Mount Holmes, Mount Ellsworth and Mount Hillers are all about 12 km in diameter, but the amplitudes of their domes are about 1.2, 1.85...
Ages and stable-isotope compositions of secondary calcite and opal in drill cores from Tertiary volcanic rocks of the Yucca Mountain area, Nevada
Barney J. Szabo, T.K. Kyser
1990, Geological Society of America Bulletin (102) 1714-1719
Stable-isotope compositions of fracture-and cavity-filling calcite from the unsaturated zone of three drill cores at Yucca Mountain Tertiary volcanic complex indicate that the water from which the minerals precipitated was probably meteoric in origin. A decrease in 18O in the calcite with depth is...
The Stillwater Complex and its anorthosites: an accident of magmatic underplating?
G.K. Czamanske, S.R. Bohlen
1990, American Mineralogist (75) 37-45
The Stillwater Complex, emplaced 2700??40 Ma, is exposed at the edge of a 4000-km2 block of Late Archean rocks that formed 40 to 110 m.y. yearlier. Voluminous plagioclase cumulates (anorthosites) within the Middle Banded series of the complex are difficult to explain either by in situ fractionation of mafic magma...
Coastal retreat and shoreface profile variations in the Canadian Beaufort Sea
A. Hequette, P. W. Barnes
1990, Marine Geology (91) 113-132
The coastline of the southern Canadian Beaufort Sea consists primarily of unconsolidated bluffs. Although the sea is ice-free for 3 months of the year and wave energy is restricted by pack ice, the coast is undergoing regional retreat with erosion rates as...
GLIMPCE Seismic reflection evidence of deep-crustal and upper-mantle intrusions and magmatic underplating associated with the Midcontinent Rift system of North America
John C. Behrendt, D. R. Hutchinson, M. Lee, C.R. Thornber, A. Trehu, W. Cannon, A. Green
1990, Tectonophysics (173) 595-615
Deep-crustal and Moho reflections, recorded on vertical incidence and wide angle ocean bottom Seismometer (OBS) data in the 1986 GLIMPCE (Great Lakes International Multidisciplinary Program on Crustal Evolution) experiment, provide evidence for magmatic underplating and intrusions within the lower crust and upper mantle contemporaneous with crustal extension in the Midcontinent...
Response of the water level in a well to Earth tides and atmospheric loading under unconfined conditions
Stuart Rojstaczer, Francis S. Riley
1990, Water Resources Research (26) 1803-1817
The response of the water level in a well to Earth tides and atmospheric loading under unconfined conditions can be explained if the water level is controlled by the aquifer response averaged over the saturated depth of the well. Because vertical averaging tends to diminish the influence of the water...
Petrology of the Rainy Lake area, Minnesota, USA-implications for petrotectonic setting of the archean southern Wabigoon subprovince of the Canadian Shield
W. C. Day
1990, Contributions to Mineralogy and Petrology (105) 303-321
The Rainy Lake area in northern Minnesota and southwestern, Ontario is a Late Archean (2.7 Ga) granite-greenstone belt within the Wabigoon subprovince of the Canadian Shield. In Minnesota the rocks include mafic and felsic volcanic rocks, volcaniclastic, chemical sedimentary rocks, and graywacke that are intrucded by coeval gabbro, tonalite, and...
Effect of ten quaternary ammonium cations on tetrachloromethane sorption to clay from water
J. A. Smith
1990, Environmental Science & Technology (24) 1167-1172
The mineral surface of Wyoming bentonite (clay) was modified by replacing inorganic ions by each of 10 quaternary ammonium compounds, and tetrachloromethane sorption to the modified sorbents from water was studied. Tetrachloromethane sorption from solution to clay modified with tetramethyl-, tetraethyl-, benzyltrimethyl-, or benzyltriethylammonium cations generally is characterized by relatively...
Geochemistry of reduced gas related to serpentinization of the Zambales ophiolite, Philippines
T.A. Abrajano, N.C. Sturchio, B. M. Kennedy, G.L. Lyon, K. Muehlenbachs, J.K. Böhlke
1990, Applied Geochemistry (5) 625-630
Methane-hydrogen gas seeps with mantle-like C and noble gas isotopic characteristics issue from partially serpentinized ultramafic rocks in the Zambales ophiolite, Philippines. New measurements of noble gas and 14C isotope abundances, rock/mixed-volatile equilibrium calculations, and previous chemical and isotopic data suggest that these reduced gases are products of periodotite hydration....
Geometry of the September 1971 eruptive fissure at Kilauea volcano, Hawaii
J.J. Dvorak
1990, Bulletin of Volcanology (52) 507-514
A three-dimensional model has been used to estimate the location and dimensions of the eruptive fissure for the 24-29 September 1971 eruption along the southwest rift zone of Kilauea volcano, Hawaii. The model is an inclined rectangular sheet embedded in an elastic half-space with constant displacement on the plane of...
Arsenic in benthic bivalves of San Francisco Bay and the Sacramento/San Joaquin River Delta
C. Johns, S. N. Luoma
1990, Science of Total Environment (97-98) 673-684
Arsenic concentrations were determined in fine-grained, oxidized, surface sediments and in two benthic bivalves, Corbicula sp. and Macoma balthica, within San Francisco Bay, the Sacramento/San Joaquin River Delta, and selected rivers not influenced by urban or industrial activity. Arsenic concentrations in all samples were characteristic of values reported for uncontaminated...
Arsenopyrite in the bank deposits of the Whitewood Creek-Belle Fourche-Cheyenne River-Lake Oahe system, South Dakota, U.S.A.
A. J. Horowitz, K. A. Elrick, R.B. Cook
1990, Conference Paper, Science of the Total Environment
Mining, milling, and processing wastes containing quantities of arsenopyrite were produced around Lead, South Dokata, from 1875 to 1977. Much of this material was discharged into Whitewood Creek, and from there portions of the waste were transported to the Belle Fourche River, thence to the Cheyenne River, and finally to...
Geochemical evidence for Se mobilization by the weathering of pyritic shale, San Joaquin Valley, California, U.S.A.
T. S. Presser, W. C. Swain
1990, Applied Geochemistry (5) 703-717
Acidic (pH 4) seeps issue from the weathered Upper Cretaceous-Paleocene marine sedimentary shales of the Moreno Formation in the semi-arid Coast Ranges of California. The chemistry of the acidic solutions is believed to be evidence of current reactions ultimately yielding hydrous...
Volcanism in the Sumisu Rift, I. Major element, volatile, and stable isotope geochemistry
A.G. Hochstaedter, J.B. Gill, M. Kusakabe, S. Newman, M. Pringle, B. Taylor, P. Fryer
1990, Earth and Planetary Science Letters (100) 179-194
A bimodal volcanic suite with KAr ages of 0.05–1.40 Ma was collected from the Sumisu Rift using alvin. These rocks are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, and provide a present day example of volcanism associated with...
Global data collection and the surveillance of active volcanoes
Peter L. Ward
1990, Global and Planetary Change (3) 263-267
Data relay systems on existing earth-orbiting satellites provide an inexpensive way to collect environmental data from numerous remote sites around the world. This technology could be used effectively for fundamental monitoring of most of the world's active volcanoes. Such global monitoring would focus attention on the most dangerous volcanoes that...
