Structure and morphology of submarine slab slides: clues to origin and behavior
Dennis W. O’Leary
1991, Marine Geotechnology (10) 53-69
Geologic features suggest that some slab slides probably result from long-term strength degradation of weak layers deep in the homoclinal section. Time-dependent strain in clay-rich layers can create potential slide surfaces of low frictional strength. Competent layers are weak in tension and probably fragment in the first instance of, or...
Porosity trends of the Lower Cretaceous J Sandstone, Denver Basin, Colorado
J. W. Schmoker, D.K. Higley
1991, Journal of Sedimentary Petrology (61) 909-920
This study examines relationships between porosity and time-temperature history, and the influence of rock properties upon porosity, for the Lower Cretaceous J Sandstone in the Colorado portion of the Denver basin. The J Sandstone is classified as a quartzarenite to litharenite and was...
Inorganic ground-water chemistry at an experimental New Albany Shale (Devonian-Mississippian) in situ gasification site
T.D. Branam, J.B. Comer, N.R. Shaffer, M.V. Ennis, S.H. Carpenter
1991, Fuel (70) 1317-1323
Experimental in situ gasification of New Albany Shale (Devonian-Mississippian) has been conducted in Clark County. Analyses of ground water sampled from a production well and nine nearby monitoring wells 3 months after a brief in situ gasification period revealed changes in water chemistry associated with the gasification procedure. Dissolved iron, calcium and sulphate in...
Habitat use, survival, and causes of mortality among mallard broods hatched near the James River in North Dakota
Gary L. Krapu, C.R. Luna
1991, Prairie Naturalist (23) 213-222
Habitat use and survival by nine mallard (Anas platyrhynchos) broods from nests on the James River floodplain and adjacent drift plain were monitored during summer 1987. Radio-marked broods were relocated an average of 22% of the time in the river channel, 22% in oxbow ponds, 43% in a large sewage...
A statistical approach to the interpretation of aliphatic hydrocarbon distributions in marine sediments
J. B. Rapp
1991, Chemical Geology (93) 163-177
Q-mode factor analysis was used to quantitate the distribution of the major aliphatic hydrocarbon (n-alkanes, pristane, phytane) systems in sediments from a variety of marine environments. The compositions of the pure end members of the systems were obtained from factor scores and the distribution of the systems within each sample...
Consolidation and erosion of deposited cohesive sediments in Northern Chesapeake Bay, USA
J. Halka, W. Panageotou, L. Sanford
1991, Geo-Marine Letters (11) 174-178
Deposits of dredged cohesive sediments were monitored for changes in volume, bulk characteristics, and susceptibility to resuspension and erosion at disposal sites in Chesapeake Bay. There is a 23-48% volume reduction during the first six months, with correspondingly greater changes over longer time periods. A bulk density increase from 1.15...
Coprecipitation mechanisms and products in manganese oxidation in the presence of cadmium
J.D. Hem, Carol J. Lind
1991, Geochimica et Cosmochimica Acta (55) 2435-2451
Manganese oxidation products were precipitated in an aerated open-aqueous system where a continuous influx of mixed Mn2+ and Cd2+ solution was supplied and pH was maintained with an automated pH-stat adding dilute NaOH. X-ray diffraction and electron diffraction identified the solids produced as mixtures of Cd2Mn34+O8, Mn2+2Mn4+3O8, MnO2 (ramsdellite), and CdCO3. Mean oxidation...
Lg and Rg waves on the California regional networks from the December 23, 1985 Nahanni earthquake
L. A. Wald, T. H. Heaton
1991, Journal of Geophysical Research (96) 12099-12125
We investigate Lg and Rg propagation in California using the central and southern California regional networks. Approximately 550 stations constitute these two short-period networks providing a dense coverage of almost the entire state. The waveforms recorded from the December 23, 1985, Nahanni, Canada, earthquake are used to construct three...
Analysis of borehole expansion and gallery tests in anisotropic rock masses
B. Amadei, W. Z. Savage
1991, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts (28) 383-396
Closed-form solutions are used to show how rock anisotropy affects the variation of the modulus of deformation around the walls of a hole in which expansion tests are conducted. These tests include dilatometer and NX-jack tests in boreholes and gallery tests in tunnels. The effects of rock anisotropy on the...
Genesis and continuity of quaternary sand and gravel in glacigenic sediment at a proposed low-level radioactive waste disposal site in east-central Illinois
K. G. Troost, B. Brandon Curry
1991, Environmental Geology and Water Sciences (18) 159-170
The Illinois Department of Nuclear Safety has characterized the Martinsville Alternative Site (MAS) for a proposed low-level radioactive waste disposal facility. The MAS is located in east-central Illinois approximately 1.6 km (1 mi) north of the city of Martinsville. Geologic investigation of the 5.5-km2 (1380-acre) site revealed a sequence of...
Proposed method of hydrogeochemical exploration for salt deposits using ClBr ratios, Eastern Province, Kingdom of Saudi Arabia
C. L. Smith
1991, Applied Geochemistry (6) 249-255
Despite the value of the salt (NaCl) and brine used by the chemical industry, geochemical prospecting techniques are not customarily employed in the search for these raw materials. In this study, Br geochemistry is used as the basis for a proposed hydrogeochemical prospecting technique that was designed to search for...
Origin of xenoliths in the trachyte at Puu Waawaa, Hualalai Volcano, Hawaii
David A. Clague, Wendy A. Bohrson
1991, Contributions to Mineralogy and Petrology (108) 439-452
Rare dunite and 2-pyroxene gabbro xenoliths occur in banded trachyte at Puu Waawaa on Hualalai Volcano, Hawaii. Mineral compositions suggest that these xenoliths formed as cumulates of tholeiitic basalt at shallow depth in a subcaldera magma reservoir. Subsequently, the minerals in the xenoliths underwent subsolidus reequilibration that particularly affected chromite...
MBSSAS: A code for the computation of margules parameters and equilibrium relations in binary solid-solution aqueous-solution systems
P. D. Glynn
1991, Computers & Geosciences (17) 907-966
The computer code MBSSAS uses two-parameter Margules-type excess-free-energy of mixing equations to calculate thermodynamic equilibrium, pure-phase saturation, and stoichiometric saturation states in binary solid-solution aqueous-solution (SSAS) systems. Lippmann phase diagrams, Roozeboom diagrams, and distribution-coefficient diagrams can be constructed from the output data files,...
Comparison of Vibroseis and explosive source methods for deep crustal seismic reflection profiling in the Basin and Range province
T.M. Brocher, P. E. Hart
1991, Journal of Geophysical Research (96) 18197-18213
Direct comparison of low-fold, high-energy explosive and high-fold, lower-energy Vibroseis methods for acquiring deep crustal seismic reflection data in the Basin and Range Province suggests that the high-fold common midpoint (CMP) method there does not provide the best possible image of lower crustal structure. During...
Intrusion of horizontal dikes: tectonic significance of Middle Proterozoic diabase sheets widespread in the upper crust of the southwestern United States
K. A. Howard
1991, Journal of Geophysical Research (96) 12461-12478
Initially horizontal sheet intrusions of Middle Proterozoic diabase are abundant in a region 650 by 300 km across in Arizona and California. The diabase forms discordant sheets in basement granite and gneiss and sills in overlying shelf sedimentary sequences. Massive granite is the most common...
Habitat use and movements of canvasback broods in southwestern Manitoba
J. E. Austin, J.R. Serie
1991, Prairie Naturalist (23) 223-228
Canvasback (Aythya valisineria) broods (n = 69) accompanying marked females were observed during five summers in southwestern Manitoba. We evaluated movements of broods of different age classes ( 14 days old, 15-28 days old, and >28 days old) among ponds of different size and wetland class. Of 202 brood sightings,...
Feeding ecology of waterfowl wintering on evaporation ponds in California
N.H. Euliss Jr., R. L. Jarvis, D.S. Gilmer
1991, Condor (93) 582-590
We examined the feeding ecology of Northern Pintails (Anas acuta), Northern Shovelers (A. clypeata), and Ruddy Ducks (Oxyura jamaicensis) wintering on drainwater evaporation ponds in California from 1982 through 1984. Pintails primarily consumed midges (Chironomidae) (39.3%) and widegeongrass (Ruppia maritima) nutlets (34.6%). Shovelers and Ruddy Ducks consumed 92.5% and 90.1%...
Petrography of Permian “Gondwana” coals from boreholes in northwestern Bangladesh, based on semiautomated reflectance scanning
Neely Bostick, William J. Betterton, Harold J. Gluskoter, Islam M. Nazrul
1991, Organic Geochemistry (17) 399-413
Drilling through Quaternary alluvium and Tertiary cover at low-gravity anomalies in northwestern Bangladesh showed the presence of Permian sedimentary rocks in depressions that may be as much as a thousand meters deep in the crystalline basement. These Permian strata include low-sulfur, high-volatile bituminous coals in beds as thick as 15...
Oligocene basaltic volcanism of the northern Rio Grande Rift: San Luis Hills, Colorado
R. A. Thompson, C.M. Johnson, H. H. Mehnert
1991, Journal of Geophysical Research (96) 13577-13592
The inception of the Rio Grande rift in northern New Mexico and southern Colorado was accompanied by voluminous mafic volcanism preserved in part as erosional remnants on an intrarift horst within the current axial rift graben of the San Luis Valley. Oligocene (∼26 Ma) volcanic...
Backwater effects in the Amazon River basin of Brazil
R.H. Meade, J.M. Rayol, S.C. Da Conceicao, J.R.G. Natividade
1991, Environmental Geology and Water Sciences (18) 105-114
The Amazon River mainstem of Brazil is so regulated by differences in the timing of tributary inputs and by seasonal storage of water on floodplains that maximum discharges exceed minimum discharges by a factor of only 3. Large tributaries that drain the southern Amazon River basin reach their peak discharges...
Statistical analyses of soil properties on a quaternary terrace sequence in the upper sava river valley, Slovenia, Yugoslavia
N. Vidic, M. Pavich, F. Lobnik
1991, Geoderma (51) 189-211
Alpine glaciations, climatic changes and tectonic movements have created a Quaternary sequence of gravely carbonate sediments in the upper Sava River Valley, Slovenia, Yugoslavia. The names for terraces, assigned in this model, Günz, Mindel, Riss and Würm in order of decreasing age, are used as morphostratigraphic terms. Soil chronosequence on...
Drought description
N.C. Matalas
1991, Stochastic Hydrology and Hydraulics (5) 255-260
What constitutes a comprehensive description of drought, a description forming a basis for answering why a drought occurred is outlined. The description entails two aspects that are "naturally" coupled, named physical and economic, and treats the set of hydrologic measures of droughts in terms of their multivariate distribution, rather than...
Weathering processes and the composition of inorganic material transported through the Orinoco River system, Venezuela and Colombia
R.F. Stallard, L. Koehnken, M. J. Johnsson
1991, Geoderma (51) 133-165
The composition of river-borne material in the Orinoco River system is related primarily to erosion regime, which in turn is related to tectonic setting; especially notable is the contrast between material derived from tectonically active mountain belts and that from stable cratonic regions. For a particular morpho-tectonic region, the compositional...
Reconciliation of stress and structural histories of the Tharsis region of Mars
K. L. Tanaka, M.P. Golombek, W.B. Banerdt
1991, Journal of Geophysical Research (96) 15617-15633
We present a new compilation of the structural and stratigraphic evolution of the Tharsis region of Mars that incorporates recent advances in understanding its stratigraphy, and we introduce a lithospheric deformation model that can account for the observations. The first period in the formation of...
A northern Cordilleran ocean-continent transect: Sitka Sound, Alaska, to Atlin Lake, British Columbia
D. A. Brew, Susan M. Karl, D.F. Barnes, R.C. Jachens, A. B. Ford, R. Horner
1991, Canadian Journal of Earth Sciences (28) 840-853
The 155 km wide, 310 km long Sitka Sound – Atlin Lake continent–ocean transect includes almost all the geologic, geophysical, and geotectonic elements of the Canadian Cordillera. It crosses the Chugach, Wrangellia, Alexander, Stikine, and Cache Creek terranes, the Gravina and Laberge overlap assemblages, intrusive and metamorphic belts, and neotectonic faults that...
