CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.
Andrew Simon, Cliff R. Hupp
1987, Transportation Research Record 16-24
This study (a) assesses the channel changes and network trends of bed level response after modifications between 1959 and 1972 of alluvial channels in western Tennessee and (b) develops a conceptual model of bank slope development to qualitatively assess bank stability and potential channel widening. A six-step, semiquantitative model of...
Natural-field and very low-frequency tipper profile interpretation of contacts
Victor F. Labson, Alex Becker
1987, Geophysics (52) 1697-1707
Anomalous vertical magnetic field (tipper) profiles acquired using natural or very low-frequency (VLF) radio transmitter sources can be interpreted simply and rapidly for a number of geologic settings. The relations between computed numerical models, and outcropping dipping and buried vertical contacts are presented here in a series of interpretation charts....
Computer simulations of large asteroid impacts into oceanic and continental sites--Preliminary results on atmospheric, cratering and ejecta dynamics
D. J. Roddy, S.H. Schuster, M. Rosenblatt, L.B. Grant, Paul J. Hassig, K.N. Kreyenhagen
1987, International Journal of Impact Engineering (5) 525-541
Computer simulations have been completed that describe passage of a 10-km-diameter asteroid through the Earth's atmosphere and the subsequent cratering and ejecta dynamics caused by impact of the asteroid into both oceanic and continental sites. The asteroid was modeled as...
Stable isotope compositions of fossil mollusks from southern California: Evidence for a cool last interglacial ocean.
D.R. Muhs, T.K. Kyser
1987, Geology (15) 119-122
Stable isotope compositions have been determined for modern mullusks and fossil mollusks collected from uplifted marine terraces at three localities in southern California. By using a paleoclimatic model that decouples the temperature and ice-volume signals in ocean water, ocean-water temperatures off southern California...
Crescentic dunes on the inner continental shelf off northern California
D.A. Cacchione, M.E. Field, D.E. Drake, G. B. Tate
1987, Geology (15) 1134-1137
Large crescentic dunes that resemble barchans have been discovered within elongate scour depressions on the northern California inner continental shelf by using side-scan sonar. These dunes appear to be migrating obliquely to the regional shelf gradient; a preferred offshore direction of transport is...
Fitting degradation of shoreline scarps by a nonlinear diffusion model
D.J. Andrews, Robert C. Bucknam
1987, Journal of Geophysical Research Solid Earth (92) 12857-12867
The diffusion model of degradation of topographic features is a promising means by which vertical offsets on Holocene faults might be dated. In order to calibrate the method, we have examined present-day profiles of wave-cut shoreline scarps of late Pleistocene lakes Bonneville and Lahontan. It may be assumed that these...
Integration of channel and floodplain suites. I. Developmental sequence and lateral relations of alluvial paleosols.
T. M. Bown, M. J. Kraus
1987, Journal of Sedimentary Petrology (57) 587-601
The lower Eocene Willwood Formation of the Bighorn Basin, northwest Wyoming, consists of about 770 m of alluvial rocks that exhibit extensive mechanical and geochemical modifications resulting from Eocene pedogenesis. Willwood paleosols vary considerably in their relative degrees of maturity; maturity is defined...
Bundled slaty cleavage in laminated argillite, north-central Minnesota
D. L. Southwick
1987, Journal of Structural Geology (9) 985-993
Exceptional bundled slaty cleavage (defined herein) has been found in drill cores of laminated, folded, weakly metamorphosed argillite at several localities in the early Proterozoic Animikie basin of north-central Minnesota. The cleavage domains are more closely spaced within the cleavage bundles...
Sulfur and lead isotope studies of stratiform Zn-Pb-Ag deposits, Anvil Range, Yukon: Basinal brine exhalation and anoxic bottom-water mixing (Canada)
Wayne C. Shanks III, L. G. Woodruff, G.A. Jilson, D.S. Jennings, J.S. Modene, B.D. Ryan
1987, Economic Geology (82) 600-634
Five stratiform Zn-Pb-Ag deposits are known in Early Cambrian metapelitic rocks along a curvilinear trend in the Anvil Range, central Yukon. The Anvil Range deposits occur along the southwestern boundary of the Selwyn basin in the stratigraphic transition zone between metapelites of the Mt. Mye unit and calcareous phyllites of...
Current loops fitted to geomagnetic model spherical harmonic coefficients.
L.R. Alldredge
1987, Journal of Geomagnetism & Geoelectricity (39) 271-296
One hundred-sixty circular current loops with radial axes were fitted by least squares to the 899 spherical harmonic coefficients of a 29th degree model. In the first case, the parameters that were fitted for each loop were the normalized magnetic moment, the distance from the center of the Earth...
Determination of the rare-earth elements in geological materials by inductively coupled plasma mass spectrometry
F.E. Lichte, Allen L. Meier, James G. Crock
1987, Analytical Chemistry (59) 1150-1157
A method of analysis of geological materials for the determination of the rare-earth elements using the Inductively coupled plasma mass spectrometric technique (ICP-MS) has been developed. Instrumental parameters and factors affecting analytical results have been first studied and then optimized. Samples are analyzed directly following an acid digestion, without the...
Gray whale and walrus feeding excavation on the Bering Shelf, Alaska
C.H. Nelson, K.R. Johnson, J. H. Barber Jr.
1987, Journal of Sedimentary Petrology (57) 419-430
Sidescan sonar has been used to delineate benthic feeding structures of the California gray whale ( Eschrichtius robustus ) and Pacific walrus ( Odobenus rosmarus divergens ) on the northeastern Bering Shelf. The gray whales (average mouth length, 2.0 m), when suction feeding...
Higher resolution satellite remote sensing and the impact on image mapping
Allen H. Watkins, June M. Thormodsgard
1987, Acta Astronautica (16) 221-232
Recent advances in spatial, spectral, and temporal resolution of civil land remote sensing satellite data are presenting new opportunities for image mapping applications. The U.S. Geological Survey's experimental satellite image mapping program is evolving toward larger scale image map products with increased information content as a result of improved image...
Magmatic history of Red Sea rifting: Perspective from the central Saudi Arabian coastal plain
J.S. Pallister
1987, Geological Society of America Bulletin (98) 400-417
A newly recognized Tertiary dike complex and comagmatic volcanic rocks exposed on the central Saudi Arabian coastal plain record early stages of magmatism related to Red Sea rifting. Intrusive and stratigraphic relationships and new potassium-argon dating indicate episodic magmatism from about 30 Ma to the present. Additional stratigraphic and radiometric...
Tidal and tidally averaged circulation characteristics of Suisun Bay, California
Lawrence H. Smith, Ralph T. Cheng
1987, Water Resources Research (23) 143-155
Availability of extensive field data permitted realistic calibration and validation of a hydrodynamic model of tidal circulation and salt transport for Suisun Bay, California. Suisun Bay is a partially mixed embayment of northern San Francisco Bay located just seaward of the Sacramento-San Joaquin Delta. The model employs a...
A compositional multiphase model for groundwater contamination by petroleum products: 2. Numerical solution
Arthur L. Baehr, M. Yavuz Corapcioglu
1987, Water Resources Research (23) 201-213
In this paper we develop a numerical solution to equations developed in part 1 (M. Y. Corapcioglu and A. L. Baehr, this issue) to predict the fate of an immiscible organic contaminant such as gasoline in the unsaturated zone subsequent to plume establishment. This solution, obtained by using a finite...
On the functional optimization of a certain class of nonstationary spatial functions
G. Christakos, P.N. Paraskevopoulos
1987, Journal of Optimization Theory and Applications (52) 191-208
Procedures are developed in order to obtain optimal estimates of linear functionals for a wide class of nonstationary spatial functions. These procedures rely on well-established constrained minimum-norm criteria, and are applicable to multidimensional phenomena which are characterized by the so-called hypothesis of inherentity. The latter requires elimination of the polynomial,...
Benthic foraminifers on the continental shelf and upper slope, Russian River area, northern California ( USA).
P. J. Quinterno, J.V. Gardner
1987, Journal of Foraminiferal Research (17) 132-152
We analyzed benthic foraminifers from 71 surface samples collected from the sea floor of the continental margin. One hundred and six different taxa were identified, and Q-mode factor analysis was used to identify assemblages. Six foraminiferal assemblage factors explain 94% of the variation in the data matrix. The Inner Shelf...
GEOGRAPHIC ESTIMATION OF RUNOFF-MODEL PARAMETERS.
Arthur R. Schmidt, Linda S. Weiss, Kevin A. Oberg
1987, Conference Paper
The U. S. Geological Survey is developing techniques to estimate and evaluate unit-hydrograph and loss-rate parameter values for rainfall-runoff models using Geographic Information System (GIS) procedures. The data base includes basin, soil, and climatological characteristics that will be stored in a GIS, and unit-hydrograph and loss-rate parameters obtained from calibration...
Behavior of sensitivities in the one-dimensional advection-dispersion equation: Implications for parameter estimation and sampling design
Debra S. Knopman, Clifford I. Voss
1987, Water Resources Research (23) 253-272
The spatial and temporal variability of sensitivities has a significant impact on parameter estimation and sampling design for studies of solute transport in porous media. Physical insight into the behavior of sensitivities is offered through an analysis of analytically derived sensitivities for the one-dimensional form of the advection-dispersion equation. When...
CONCEPTUAL MODELS FOR THE LASSEN HYDROTHERMAL SYSTEM.
S. E. Ingebritsen, M.L. Sorey
1987, Bulletin. Geothermal Resources Council (16) 3-9
The Lassen hydrothermal system, like a number of other systems in regions of moderate to great topographic relief, includes steam-heated features at higher elevations and high-chloride springs at lower elevations, connected to and fed by a single circulation system at depth. Two conceptual models for such systems are presented. They...
Gravitational stresses in anisotropic rock masses
B. Amadei, W. Z. Savage, H.S. Swolfs
1987, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts (24) 5-14
This paper presents closed-form solutions for the stress field induced by gravity in anisotropic rock masses. These rocks are assumed to be laterally restrained and are modelled as a homogeneous, orthotropic or transversely isotropic, linearly elastic material. The analysis, constrained by the thermodynamic requirement that strain energy be positive definite,...
EMBANKMENT-DAM BREACH PARAMETERS.
David C. Froehlich
1987, Conference Paper
The study used data from 43 embankment-dam failures to develop equations that predict breach formation model parameters. These data include the failure mode, embankment characteristics, reservoir conditions at the time of failure, geometry of the final breach, and the time taken to form the breach. Regression equations were developed to...
Langrangian model of nitrogen kinetics in the Chattahoochee River
H.E. Jobson
1987, Journal of Environmental Engineering (113) 223-242
A Lagrangian reference frame is used to solve the convection‐dispersion equation and interpret water‐quality data obtained from the Chattahoochee River. The model was calibrated using unsteady concentrations of organic nitrogen, ammonia, and nitrite plus nitrate obtained during June 1977 and verified using data obtained during August 1976. Reaction kinetics of...
15N/14N variations in Cretaceous Atlantic sedimentary sequences: Implication for past changes in marine nitrogen biogeochemistry
G.H. Rau, M.A. Arthur, W.E. Dean
1987, Earth and Planetary Science Letters (82) 269-279
At two locations in the Atlantic Ocean (DSDP Sites 367 and 530) early to middle Cretaceous organic-carbon-rich beds (“black shales”) were found to have significantly lower δ15N values (lower15N/14N ratios) than adjacent organic-carbon-poor beds (white limestones or green claystones). While these lithologies are of marine origin, the black strata in...
