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Page 5252, results 131276 - 131300

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R. Wydoski, L. Emery
L.A. Nielsen, D.L. Johnson, editor(s)
1983, Book chapter, Fisheries Techniques
No abstract available at this time...
Subdivision of the Mg-suite noritic rocks into Mg-gabbronorites and Mg-norites
O.B. James, M.K. Flohr
1983, Journal of Geophysical Research Solid Earth (88) A603-A614
Mg-suite noritic rocks can be divided into two groups, the Mg-gabbronorites and the Mg-norites. The rocks of these groups differ in ratios of high-Ca pyroxene to total pyroxene, compositions of pyroxene and plagioclase, assemblages of Ti-, Nb-, and Zr-bearing minerals, compositions of chrome spinel, bulk-rock Ti/Sm and Sc/Sm, and measured...
Seasat synthetic aperture radar ( SAR) response to lowland vegetation types in eastern Maryland and Virginia
M. D. Krohn, N.M. Milton, D. B. Segal
1983, Journal of Geophysical Research - Oceans (88) 1937-1952
Examination of SEASAT SAR images of eastern Maryland and Virginia reveals botanical distinctions between vegetated lowland areas and adjacent upland areas. Radar returns from the lowland areas can be either brighter or darker than returns from the upland forests. Scattering models and scatterometer measurements predict an increase of 6 dB...
Liquefaction sites, Imperial Valley, California.
T. L. Youd, M.J. Bennett
1983, Journal of Geotechnical Engineering (109) 440-457
Sands that did and did not liquefy at two sites during the 1979 Imperial Valley, Calif., earthquake (ML = 6.6) are identified and their properties evaluated. SPT tests were used to evaluate liquefaction susceptibility. Loose fine sands in an abandoned channel liquefied and produced sand boils, ground fissures, and a...
Storm-controlled oblique dunes of the Oregon coast
R. E. Hunter, B. M. Richmond, T. R. Alpha
1983, Geological Society of America Bulletin (94) 1450-1465
The large (mean height 25 m, spacing 300 m), relatively straight-crested dunes of the central Oregon coast migrate an average of 3.8 m/yr toward an azimuth of 26°. The dunes are transverse to the strong, south-southwesterly winter storm winds that are responsible for...
A note on the chemistry of seawater in the range 350°-500°C
James L. Bischoff, Robert J. Rosenbauer
1983, Geochimica et Cosmochimica Acta (47) 139-144
The chemistry of seawater at conditions of 350° to 500°C, 220 to 1000 bars (22 to 100 MPa) is controlled by reactions involving magnesium hydroxide sulfate (MHSH) and anhydrite. During progressive heating from 350° to 500°C at 1000 bars (100 MPa), MHSH with a <img class="imgLazyJSB inlineImage" title="" src="http://ars.els-cdn.com/content/image/1-s2.0-0016703783900984-si1.gif"...
Origin of concretionary Mn-Fe-oxides in stream sediments of Maine, U.S.A.
G.A. Nowlan, J. B. McHugh, T. D. Hessin
1983, Chemical Geology (38) 141-156
Studies of stream and sediment-pore waters largely explain the genesis of concretionary Mn-Fe-oxides in Maine. Waters of two small streams near Jackman, Maine, were studied in terms of pH, Eh, dissolved oxygen, dissolved organic carbon, dissolved Mn, total dissolved Fe, and ferrous and ferric Fe. Pyrite Creek has profuse concretions...
Development of reaction models for ground-water systems
Niel Plummer, D.L. Parkhurst, D.C. Thorstenson
1983, Geochimica et Cosmochimica Acta (47) 665-685
Methods are described for developing geochemical reaction models from the observed chemical compositions of ground water along a hydrologic flow path. The roles of thermodynamic speciation programs, mass balance calculations, and reaction-path simulations in developing and testing reaction models are contrasted. Electron transfer is included in the mass balance equations...
River discharge controls phytoplankton dynamics in the northern San Francisco Bay estuary
J. E. Cloern, A.E. Alpine, B.E. Cole, R.L.J. Wong, J.F. Arthur, M.D. Ball
1983, Estuarine, Coastal and Shelf Science (16) 415-429
Phytoplankton dynamics in the upper reach of the northern San Francisco Bay estuary are usually characterized by low biomass dominated by microflagellates or freshwater diatoms in winter, and high biomass dominated by neritic diatoms in summer. During two successive years of very low river discharge (the drought of 1976-77), the...
Authigenic vivianite in Potomac River sediments: control by ferric oxy-hydroxides
P.P. Hearn, D.L. Parkhurst, E. Callender
1983, Journal of Sedimentary Petrology (53) 165-177
Sand-size particles of vivianite (Fe 3 (PO 4 ) 2 .8H 2 O) have been identified in surficial sediments of the tidal Potomac River near a major sewage treatment plant. Vivianite is concentrated in a surface layer of coarse-sand dredge spoil, which overlies much finer sediment. Although saturation indices indicate that...
Progressive changes in the morphology of fluvial terraces and scarps along the Rappahannock River, Virginia.
Steven M. Colman
1983, Earth Surface Processes and Landforms (8) 201-212
Progressive geomorphic changes in the flight of fluvial terraces along the Rappahannock River, Virginia, provide a framework for analysing the effect of time on landforms. Indices of terrace preservation, especially drainage densities and area to perimeter ratios, show systematic changes with terrace age. Higher scarps tend to have steeper slopes...
Selective concentration of cesium in analcime during hydrothermal alteration, Yellowstone National Park, Wyoming
T. E. C. Keith, J. M. Thompson, R. E. Mays
1983, Geochimica et Cosmochimica Acta (47) 795-804
Chemical and mineralogical studies of fresh and hydrothermally altered rhyolitic material in Upper and Lower Geyser Basins, Yellowstone National Park, show that all the altered rocks are enriched in Cs and that Cs is selectively concentrated in analcime. The Cs content of unaltered rhyolite lava flows, including those from which...
Carbonatite tuffs in the Laetolil Beds of Tanzania and the Kaiserstuhl in Germany
R. L. Hay, J. R. O’Neil
1983, Contributions to Mineralogy and Petrology (82) 403-406
Carbonatite lava and tephra are now well known. The only modern eruptive carbonatites, from Oldoinyo Lengai, Tanzania, are of alkali carbonatite, whereas all of the pre-modern examples are of calcite or dolomite. Chemical and stable isotope analyses were made of separate phases of Pliocene carbonatite tuffs of the Laetolil Beds...
Ground water for oil-shale development, Piceance Basin, Colorado
W.M. Alley
1983, Ground Water (21) 456-464
Vast deposits of oil shale are contained in the Piceance basin in northwestern Colorado. The basin may contain as much as 40 million acre-feet of stored water associated with these deposits, much of which may have to be drained for mining. Yet, most analyses of...
Crustal and upper mantle structure of the northern and central Sierra Nevada
B.B. Mavko, G. A. Thompson
1983, Journal of Geophysical Research Solid Earth (88) 5874-5892
Teleseismic data were recorded within the Sierra Nevada to look for lateral variations in the upper mantle. The data were collected at both temporary and permanent stations, and P wave residuals were computed. After correcting the P residual data for crustal and topographic effects, there is still a variation of as much as 0.5-0.6...
In situ capture gamma-ray analysis of coal in an oversize borehole
J.L. Mikesell, D.W. Dotson, F. E. Senftle, R.S. Zych, J. Koger, L. Goldman
1983, Nuclear Instruments and Methods In Physics Research (215) 561-566
In situ capture gamma-ray analysis in a coal seam using a high resolution gamma-ray spectrometer in a close-fitting borehole has been reported previously. In order to check the accuracy of the method under adverse conditions, similar measurements were made by means of a small-diameter sonde in an oversize borehole in...
Paleotemperature oscillations in the Middle and Late Miocene of the northeastern Pacific.
J.A. Barron, G. Keller
1983, Micropaleontology (29) 150-181
The paleoclimatic and paleoceanographic history has been studied in a N-S transect encompassing DSDP Site 173, the Newport Beach surface section, and DSDP Site 470, based on quantitative diatom and planktic foraminiferal analyses. Fourteen cold and 12 warm events that show close agreement with other microfossil studies as well as...
Nitrate concentrations under irrigated agriculture
A. Zaporozec
1983, Environmental Geology (5) 35-38
In recent years, considerable interest has been expressed in the nitrate content of water supplies. The most notable toxic effect of nitrate is infant methemoglobinemia. The risk of this disease increases significantly at nitrate-nitrogen levels exceeding 10 mg/l. For this reason, this concentration has been established as a limit for...
Requirements for modeling trace metal partitioning in oxidized estuarine sediments
Samuel N. Luoma, J.A. Davis
1983, Marine Chemistry (12) 159-181
The fate of particulate-bound metals is of particular importance in estuaries because major biological energy flows involve consumption of detrital particles. The biological impact of particulate-bound metals is strongly influenced by the partitioning of metals among sediment components at the oxidized sediment-water interface. Adequate methods for directly measuring this partitioning...
Thermal areas on Kilauea and Mauna Loa Volcanoes, Hawaii
Thomas J. Casadevall, Richard W. Hazlett
1983, Journal of Volcanology and Geothermal Research (16) 173-188
Active thermal areas are concentrated in three areas on Mauna Loa and three areas on Kilauea. High-temperature fumaroles (115-362°C) on Mauna Loa are restricted to the summit caldera, whereas high-temperature fumaroles on Kilauea are found in the upper East Rift Zone (Mauna Ulu summit fumaroles, 562°C), middle East Rift Zone...