Crustal velocities near Coalinga, California, modeled from a combined earthquake/explosion refraction profile
N. Macgregor-Scott, A. Walter
1988, Bulletin of the Seismological Society of America (78) 1475-1490
Crustal velocity structure for the region near Coalinga, California, has been derived from both earthquake and explosion seismic phase data recorded along a NW-SE seismic-refraction profile on the western flank of the Great Valley east of the Diablo Range. Comparison of the two data sets reveals P-wave phases in common...
A New Species of Pulvinites (Mollusca: Bivalvia) from the Upper Paleocene Paspotansa Member of the Aquia Formation in Virginia
L. W. Ward, T.R. Waller
1988, Journal of Paleontology (62) 51-55
Pulvinites lawrencei n.sp. is described from the upper Paleocene (Landenian Stage) Paspotansa Member of the Aquia Formation in Stafford County, Virginia. This is the first report of a member of the pteriacean family Pulvinitidae in the Tertiary on either side of the Atlantic, the only other post-Mesozoic records of Pulvinites...
Seismic imaging of extended crust with emphasis on the western United States
J. McCarthy, G. A. Thompson
1988, Geological Society of America Bulletin (100) 1361-1374
Understanding of the crust has improved dramatically following the application of seismic reflection and refraction techniques to studies of the deep crust. This is particularly true in areas where the last tectonic event was extensional, such as the Basin and Range province of the western United States and much of...
Chemistry and geothermometry of brine produced from the Salton Sea Scientific drill hole, Imperial Valley, California
J. M. Thompson, R.O. Fournier
1988, Journal of Geophysical Research Solid Earth (93) 13165-13173
The December 29–30, 1985, flow test of the State 2–14 well, also known as the Salton Sea Scientific drill hole, produced fluid from a depth of 1865–1877 m at a reservoir temperature of 305° ± 5°C. Another flow test at a depth of 3170 m produced brine contaminated by drilling...
Upper mantle electrical conductivity for seven subcontinental regions of the Earth
W.H. Campbell, E.R. Schiffmacher
1988, Journal of Geomagnetism & Geoelectricity (40) 1387-1406
Spherical harmonic analysis coefficients of the external and internal parts of the quiet-day geomagnetic field variations (Sq) separated for the seven continental regions of the observatories have been used to determine conductivity profiles to depths of about 600km by the Schmucker equivalent substitute conductor method. The profiles give...
General two‐point method for Determining velocity in open channel
John F. Walker
1988, Journal of Hydraulic Engineering (114) 801-805
The generally accepted procedure is to average velocity measurements at 0. 2D and 0. 8D, measured vertically from the water surface,or alternatively to measure velocity at a position equal to 0. 6D, where D is the total depth of flow. In some situations, one may wish to measure at depths...
Downslope Eulerian mean flow associated with high-frequency current fluctuations observed on the outer continental shelf and upper slope along the northeastern United States continental margin: Implications for sediment transport
B. Butman
1988, Continental Shelf Research (8) 811-840
Eulerian current measurements made 5-7 m above bottom at six stations along the United States east coast continental margin show a net downslope flow of 1-5 cm s-1. Although the scalar current speed decreases with water depth and toward the bottom, fluctuations in the cross-isobath flow were stronger and increasingly...
Stratigraphy and magnetic polarity of the high terrace remnants in the upper Ohio and Monongahela Rivers in West Virginia, Pennsylvania, and Ohio
R. B. Jacobson, D. P. Elston, John W. Heaton
1988, Quaternary Research (29) 216-232
A synthesis of previous work and new data on the stratigraphy of high terraces of the Ohio and Monongahela Rivers upstream from Parkersburg, West Virginia, indicates a correspondence between terrace histories in the ancient Teays and Pittsburgh drainage basins. Four terraces are identified in each. Sediments of the lower three...
The northeastern Ohio earthquake of 31 January 1986: Was it induced?
C. Nicholson, E. Roeloffs, R. L. Wesson
1988, Bulletin of the Seismological Society of America (78) 188-217
On 31 January 1986, at 11:46 EST, an earthquake of mb = 5.0 occurred about 40 km east of Cleveland, Ohio, and about 17 km south of the Perry Nuclear Power Plant. The earthquake was felt over a broad area, including 11 states, the District of Columbia, and parts of...
Making maps with computers
S.C. Guptill, L.E. Starr
1988, American Scientist (76) 136-142
Soon after their introduction in the 1950s, digital computers were used for various phases of the mapping process, especially for trigonometric calculations of survey data and for orientation of aerial photographs on map manuscripts. In addition, computer-controlled plotters were used to draw simple outline maps. The process of collecting data...
Taolin Zn-Pb-fluorite deposit, People's Republic of China: An example of some problems in fluid inclusion research on mineral deposits
E. Roedder, K.W. Howard
1988, Journal of the Geological Society (145) 163-174
The large Taolin zinc–lead–fluorite deposit in the People’s Republic of China was discovered 28 years ago, but whether its genetic affiliation is Mississippi Valley-type, epithermal, or mesothermal has remained uncertain. Both the ore and gangue (cherty to coarse quartz, plus barite, chlorite and calcite) occur as open space filling in...
Paleoseismicity and neotectonics of the Cordillera Blanca fault zone, northern Peruvian Andes
David P. Schwartz
1988, Journal of Geophysical Research Solid Earth (93) 4712-4730
The Cordillera Bianca fault zone is a major west dipping normal fault that bounds the west side of a 120- to 170-km-wide zone of active extension along the crest of the northern Peruvian Andes. The fault is approximately 210 km long and exhibits continuous geomorphic evidence of repeated late Pleistocene...
Physical deposit measures and commercial potential: The case of titanium-bearing heavy-mineral deposits
E. D. Attanasi, J.H. DeYoung Jr.
1988, Mathematical Geology (20) 97-110
Physical measures of mineral deposit characteristics, such as grade and tonnage, long have been used in both subjective and analytic models to predict favorability of areas for the occurrence of mineral deposits of particular types. After a deposit has been identified, however, the explorationist must decide whether to continue data...
Coarse-sediment bands on the inner shelf of southern Monterey Bay, California
R. E. Hunter, J.R. Dingler, R. J. Anima, B. M. Richmond
1988, Marine Geology (80) 81-98
Bands of coarse sand that trend parallel to the shore, unlike the approximately shore-normal bands found in many inner shelf areas, occur in southern Monterey Bay at water depths of 10–20 m, less than 1 km from the shore. The bands are 20–100 m wide and alternate with bands...
Analytical approach to calculation of response spectra from seismological models of ground motion
Erdal Safak
1988, Earthquake Engineering and Structural Dynamics (16) 121-134
An analytical approach to calculate response spectra from seismological models of ground motion is presented. Seismological models have three major advantages over empirical models: (1) they help in an understanding of the physics of earthquake mechanisms, (2) they can be used to predict ground motions for future earthquakes and (3)...
Sediment yield and spurious correlation-toward a better portrayal of the annual suspendend-sediment load of rivers
C. F. Waythomas, G. P. Williams
1988, Geomorphology (1) 309-316
Bivariate relations between annual sediment yield (tons per year per unit drainage area) and drainage-basin area are spurious because drainage-basin area is common to both axes. Two alternative methods for portraying the annual suspended-sediment load of a river are suggested. One...
Stochastic system identification in structural dynamics
Erdal Safak
1988, Conference Paper
Recently, new identification methods have been developed by using the concept of optimal-recursive filtering and stochastic approximation. These methods, known as stochastic identification, are based on the statistical properties of the signal and noise, and do not require the assumptions of current methods. The criterion for stochastic system identification is...
Three-dimensional gravity modeling of the geologic structure of Long Valley caldera
S. F. Carle
1988, Journal of Geophysical Research Solid Earth (93) 13237-13250
A 48-mGal gravity low coincides with Long Valley caldera and is mainly attributed to low-density caldera fill. Gravity measurements by Unocal Geothermal have been integrated with U.S. Geological Survey data, vastly improving gravity station coverage throughout the caldera. A strong regional gravity trend is mainly attributed to isostasy. A “best...
Depositional models for two Tertiary coal-bearing sequences in the Powder River Basin, Wyoming, USA
Peter D. Warwick, Ronald W. Stanton
1988, Journal of the Geological Society (145) 613-620
Depositional controls on peat-forming environments which produce thick (>10m) coal beds can be inferred from relationships between coal bed geometry, maceral composition and associated lithologies. Study of these relationships within sedimentary sequences associated with the Wyodak-Anderson (Palaeocene) and the Felix (Eocene) sub-bituminous coal beds in the Powder River Basin,...
Regional assessment of pumpage in southeastern Virginia
Pixie A. Hamilton
1988, Conference Paper
A U.S. Geological Survey investigation was conducted, in cooperation with the Virginia Water Control Board, to analyze the hydrogeology and groundwater flow system in the Coastal Plain physiographic province of southeastern Virginia, and to assess the continued reliability of groundwater as a freshwater resource. To provide a more detailed analysis...
Stratigraphy, petrology, and provenance of the Albian Blackleaf Formation and the Cenomanian to Turonian lower part of the Frontier Formation in part of Beaverhead and Madison Counties, Montana
T. S. Dyman, W. J. Perry Jr., D. J. Nichols
1988, Mountain Geologist (25) 113-128
The units constitute a dominantly clastic sequence of sandstone, conglomerate, mudstone, and shale deposited in (west) to shallow marine (east) environments. Petrologic and paleocurrent data support an interpretation that Blackleaf and lower Frontier debris was derived from different source areas. -from Authors...
Sandstone porosity as a function of thermal maturity
J. W. Schmoker, D. L. Gautier
1988, Geology (16) 1007-1010
Sandstone porosity decreases in the subsurface as a power function of thermal maturity: ϕ = A(M)B, where ϕ is porosity and M is a measure of thermal maturity representing integrated time-temperature history; A and B are constants for a given sandstone of homogeneous properties but...
Nitrogen cycling between sediment and the shallow-water column in the transition zone of the Potomac River and estuary. I. Nitrate and ammonium fluxes
N.S. Simon
1988, Estuarine, Coastal and Shelf Science (26) 483-497
A three-year study of seasonal variation in water-column and sediment nitrogen species was conducted in the transition zone of the Potomac River 35 m from the Virginia shore at a site with an average water-column depth of approximately 1 m over sandy sediment. A diffusion-controlled sampler was used to collect...
Wetland Boundary Determination in the Great Dismal Swamp Using Weighted Averages
Virginia Carter, Mary Keith Garrett, Patricia T. Gammon
1988, Water Resources Bulletin (24) 297-306
A weighted average method was used to analyze transition zone vegetation in the Great Dismal Swamp to determine if a more uniform determination of wetland boundaries can be made nationwide. The method was applied to vegetation data collected on four transects and three vertical layers across the wetland-to-upland transition zone...
The potential for catastrophic dam failure at Lake Nyos maar, Cameroon
J. P. Lockwood, J. E. Costa, M. L. Tuttle, J. Nni, S.G. Tebor
1988, Bulletin of Volcanology (50) 340-349
The upper 40 m of Lake Nyos is bounded on the north by a narrow dam of poorly consolidated pyroclastic rocks, emplaced during the eruptive formation of the Lake Nyos maar a few hundred years ago. This 50-m-wide natural dam is structurally weak and is being eroded at an uncertain,...
