Gabbroic xenoliths from the northern Gorda Ridge: Implications for magma chamber processes under slow spreading centers
A. S. Davis, D.A. Clague
1990, Journal of Geophysical Research Solid Earth (95) 10885-10905
Abundant gabbroic xenoliths in porphyritic pillow basalt were dredged from the northern Gorda Ridge. The host lava is a moderately fractionated, normal mid-ocean ridge basalt with a heterogeneous glass rind (Mg numbers 56-60). Other lavas in the vicinity range from near primary (Mg number 69) to fractionated (Mg number 56)....
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...
The initial instability and finite-amplitude stability of alternate bars in straight channels
Jonathan M. Nelson
1990, Earth-Science Reviews (29) 97-115
The initial instability and fully developed stability of alternate bars in straight channels are investigated using linearized and nonlinear analyses. The fundamental instability leading to these features is identified through a linear stability analysis of the equations governing the flow and sediment transport fields. This instability is explained in terms...
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...
Toxicokinetics of PAHs in Hexagenia
Guy R. Stehly, Peter F. Landrum, Mary G. Henry, C. Klemm
1990, Environmental Toxicology and Chemistry (9) 167-174
The accumulation kinetics of two waterborne polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene (BAP) and phenanthrene (PHE), were studied in the mayfly nymph (Hexagenia limbata). The uptake clearance decreased while the bioconcentration of BAP increased with an increase in weight of the H. limbata nymph. The relationship between uptake clearance and bioconcentration for PHE was...
Thrust-ridge paleodepositional model for the Upper Freeport coal bed and associated clastic facies, Upper Potomac coal field, Appalachian Basin, U.S.A.
Edward S. Belt, P.C. Lyons
1990, International Journal of Coal Geology (16) 167-170
A blind-thrust-ridge model is proposed to explain the lack of coarse clastic material in the vast minable Upper Freeport coal bed (UF). This coal bed contains only fine elastic partings and is overlain by regionally extensive, closely spaced channel-belt deposits in...
Application of the DR3M watershed model on a small urban basin
Richard P. Thomas
1990, Water Resources Bulletin (26) 757-766
Data collected at a 79-acre urban watershed in Albuquerque, New Mexico, were used to calibrate and verify the Distributed Routing Rainfall-Runoff Model, a parametric watershed model. Standard errors of estimate for the 38 calibration storms were 33 percent and 38 percent, respectively, for volumes and peaks; and for the 46...
Solid-solution aqueous-solution equilibria: Thermodynamic theory and representation
P. D. Glynn, E.J. Reardon
1990, American Journal of Science (290) 164-201
Thorstenson and Plummer's (1977) "stoichiometric saturation' model is reviewed, and a general relation between stoichiometric saturation Kss constants and excess free energies of mixing is derived for a binary solid-solution B1-xCxA: GE = RT[ln Kss - xln(xKCA) - (l-x)ln((l-x)KBA)]. This equation allows a suitable excess free energy function, such as...
Cooling rate and thermal structure determined from progressive magnetization of the dacite dome at Mount St. Helens, Washington
D. Dzurisin, R.P. Denlinger, J. G. Rosenbaum
1990, Journal of Geophysical Research Solid Earth (95) 2763-2780
Our study of a magnetic anomaly associated with the recently active dacite dome at Mount St. Helens suggests that the dome consists of a hot, nonmagnetized core surrounded by a cool, magnetized carapace and flanking talus. The talus does not contribute to the anomaly because...
Comment on "The surface of lo: A new model" by Bruce Hapke
A. S. McEwen, J. I. Lunine
1990, Icarus (84) 268-274
Hapke (1989, Icarus 79, 56–74) proposed that the surface of Io is dominantly basaltic with thin coatings of polysulfur oxide, S2O, ad SO,2. However, observations and models of the active volcanism indicate that volatiles such as sulfur and SO2 must be more abundant than envisioned by Hapke....
Integration of potential-field and digital geologic data for two North American geoscience transects
J. D. Phillips
1990, Journal of Geological Education (38) 330-338
Two North American contributions to the Global Geoscience Transects Program, the Quebec-Maine-Gulf of Maine transect and the Great Lakes portion of the United States-Canadian Border transect, are among the first to produce digital geology in a form that can be combined with gridded gravity and aeromagnetic data. Maps of shaded...
Numerical simulation of hydrothermal circulation in the Cascade Range, north-central Oregon
S. E. Ingebritsen, K.M. Paulson
1990, Conference Paper, Transactions - Geothermal Resources Council
Alternate conceptual models to explain near-surface heat-flow observations in the central Oregon Cascade Range involve (1) an extensive mid-crustal magmatic heat source underlying both the Quaternary arc and adjacent older rocks or (2) a narrower deep heat source which is flanked by a relatively shallow conductive heat-flow anomaly caused by...
Berriasian (Early Cretaceous) radiometric ages from the Grindstone Creek Section, Sacramento Valley, California
T.J. Bralower, K.R. Ludwig, J. D. Obradovich
1990, Earth and Planetary Science Letters (98) 62-73
The Grindstone Creek Section, Glenn County, Northern California is a sequence of hemipelagic mudstone, siltstone and sandstone interbedded with concretionary limestone and a few thin tuffs and bentonites. Two tuffs have been collected from a narrow interval of this sequence and...
Geological interpretation of combined Seabeam, Gloria and seismic data from Anegada Passage (Virgin Islands, north Caribbean)
I. Jany, Kathryn M. Scanlon, A. Mauffret
1990, Marine Geophysical Research (12) 173-196
The Anegada Passage (sensu lato) includes several basins and ridges from Southeast of Puerto Rico to the corner of the Virgin Islands Platform. Seabeam (Seacarib I) and Gloria long-range sidescan sonar surveys were carried out in this area. These new data allow us to propose an interpretation of the Anegada...
High-resolution reflectance spectra of Mars in the 2.3-μm region: evidence for the mineral scapolite
Roger N. Clark, Gregg A. Swayze, Robert B. Singer, James B. Pollack
1990, Journal of Geophysical Research (95) 14463-14480
patially resolved reflectance spectra of Mars in the 2.2- to 2.4-μm spectral region were obtained in August 1988 using the NASA 3-m Infrared Telescope Facility. The spectra show weak absorption features due to Martian atmospheric carbon monoxide and a surface mineral. Both CO and the mineral absorptions are composed of...
Climate factor for small-basin flood frequency
R.W. Lichty, M.R. Karlinger
1990, Water Resources Bulletin (26) 577-586
A climate factor, CT, (T = 2-, 25-, and 100-year recurrence intervals) that delineates regional trends in small-basin flood frequency was derived using data from 71 long-term rainfall record sites. Values of CT at these sites were developed by a regression analysis that related rainfall-runoff model estimates of T-year floods...
Horizontal ground deformation patterns and magma storage during the Puu Oo eruption of Kilauea volcano, Hawaii: episodes 22-42
J.P. Hoffmann, G. E. Ulrich, M.O. Garcia
1990, Bulletin of Volcanology (52) 522-531
Horizontal ground deformation measurements were made repeatedly with an electronic distance meter near the Puu Oo eruption site approximately perpendicular to Kilauea's east rift zone (ERZ) before and after eruptive episodes 22-42. Line lengths gradually extended during repose periods and rapidly contracted about the same amount following eruptions. The repeated...
Volcano hazard mitigation program in Indonesia
A. Sudradjat
1990, Earthquakes & Volcanoes (USGS) (22) 227-229
Volcanological investigations in Indonesia were started in the 18th century, when Valentijn in 1726 prepared a chronological report of the eruption of Banda Api volcno, Maluku. Modern and intensive volcanological studies did not begin until the catastrophic eruption of Kelut volcano, East Java, in 1919. The eruption took 5,011 lives...
Order and diversity in the modes of circum-Pacific earthquake recurrence
W. Thatcher
1990, Journal of Geophysical Research Solid Earth (95) 2609-2623
Recurrence characteristics of great circum-Pacific earthquakes and determinations of spatial distribution of seismic moment release are surveyed in order to delineate their general features and relate earthquake slip distribution to models of recurrent rupture. As noted by others, the pattern of moment release is typically very irregular, with strong concentrations...
Three-dimensional P and S velocity structure in the Coalinga Region, California
D. Eberhart-Phillips
1990, Journal of Geophysical Research Solid Earth (95) 15343-15363
The Coalinga earthquake sequence of 1983 provided a unique opportunity to perform a three-dimensional velocity and hypocenter inversion in an area of complex three-dimensional structure dominated by folding and blind thrusts. Additionally, since other varied geological and geophysical studies have been completed in this area, the three-dimensional inversion solution could...
Changes in Wisconsin's Lake Michigan salmonid sport fishery, 1969-1985
Michael J. Hansen, Paul T. Schultz, Becky A. Lasee
1990, North American Journal of Fisheries Management (10) 442-457
The modern sport fishery for salmonids in Wisconsin waters of Lake Michigan was begun during 1963-1969 with the stocking of rainbow trout (Oncorhynchus mykiss), lake trout (Salvelinus namaycush), brook trout (S. fontinalis), brown trout (Salmo trutta), coho salmon (O. kisutch), and chinook salmon (O. tshawytscha). The fishery grew rapidly...
Effect of pH on the accumulation kinetics of pentachlorophenol in goldfish
G. R. Stehly, W. L. Hayton
1990, Archives of Environmental Contamination and Toxicology (19) 464-470
The kinetics of accumulation of pentachlorophenol (PCP) at various pH values were investigated to explore how pH-dependent accumulation might influence PCP toxicity. Goldfish (Carassius auratus) were exposed to 5 μg PCP/L in a static system buffered with 7.5 mM bicine orN,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid (BES) at pH 7.0, 8.0, or 9.0....
Age and paleoclimatic significance of the Stansbury shoreline of Lake Bonneville, Northeastern Great Basin
Charles G. Oviatt, D.R. Currey, D. M. Miller
1990, Quaternary Research (33) 291-305
The Stansbury shoreline, one of the conspicuous late Pleistocene shorelines of Lake Bonneville, consists of tufa-cemented gravel and barrier beaches within a vertical zone of about 45 m, the lower limit of which is 70 m above the modern average level of Great Salt Lake. Stratigraphic evidence at a number...
The extraordinary radar echoes from Europa, Ganymede, and Callisto: A geological perspective
S.J. Ostro, E.M. Shoemaker
1990, Icarus (85) 335-345
This outline of plausible geologic explanations for the icy Galilean satellites' radar properties takes into consideration electromagnetic scattering models for the echoes, available empirical and theoretical information about regolith formation, and ice physics. The...
Denitrification in sediments from the hyporheic zone adjacent to a small forested stream
J.H. Duff, F.J. Triska
1990, Canadian Journal of Fisheries and Aquatic Sciences (47) 1140-1147
Denitrifying potentials increased with increasing distance from the stream channel. Dissolved oxygen was 100% of the concentration expected in equilibrium with the atmosphere in water obtained from monitoring wells immediately adjacent to the stream but was as low as 7% of the expected value in water 11.4 m inland. Both...
