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Page 4356, results 108876 - 108900

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Nd, Sr, and O isotopic variations in metaluminous ash-flow tuffs and related volcanic rocks at the Timber Mountain/Oasis Valley Caldera, Complex, SW Nevada: implications for the origin and evolution of large-volume silicic magma bodies
G. L. Farmer, D.E. Broxton, R.G. Warren, W. Pickthorn
1991, Contributions to Mineralogy and Petrology (109) 53-68
Nd, Sr and O isotopic data were obtained from silicic ash-flow tuffs and lavas at the Tertiary age (16-9 Ma) Timber (Mountain/Oasis Valley volcanic center (TMOV) in southern Nevada, to assess models for the origin and evolution of the large-volume silicic magma bodies generated in this region. The large-volume (>900...
A lead isotopic study of the Stillwater Complex, Montana: constraints on crustal contamination and source regions
J. L. Wooden, G.K. Czamanske, M. L. Zientek
1991, Contributions to Mineralogy and Petrology (107) 80-93
Analyses of the Pb isotopic compositions of plagioclase from 23 samples covering the stratigraphic thickness of the Stillwater Complex indicate a narrow range of apparent initial isotopic compositions (206Pb/ 204Pb=13.95; 207Pb/204Pb=14.95-15.01; 208Pb/204Pb=33.6). The uniformity of our data is in contrast to, but not necessarily contradictory to, other recent investigations which...
Vertical structure of cross-shore currents from wind-induced setup
Guy Gelfenbaum
1991, Conference Paper, Coastal Sediments '91
Most of the storm surge models presented in the literature are vertically averaged and calculate only the sea-surface elevation and mean flow. Whereas these models may be adequate for predicting storm surge heights for flooding purposes, they neglect the vertical structure of the flow and the boundary shear stress, which...
The Reaction Titanite+Kyanite=Anorthite+Rutile and Titanite-Rutile Barometry in Eclogites
C.F. Manning, S.R. Bohlen
1991, Contributions to Mineralogy and Petrology (109) 1-9
Titanite and rutile are a common mineral pair in eclogites, and many equilibria involving these phases are potentially useful in estimating pressures of metamorphism. We have reversed one such reaction, {Mathematical expression} using a piston-cylinder apparatus. Titanite+kyanite is the high-pressure assemblage and our results locate the equilibrium between 15.5 15.9,...
An exact solution of solute transport by one-dimensional random velocity fields
V.D. Cvetkovic, G. Dagan, A.M. Shapiro
1991, Stochastic Hydrology and Hydraulics (5) 45-54
The problem of one-dimensional transport of passive solute by a random steady velocity field is investigated. This problem is representative of solute movement in porous media, for example, in vertical flow through a horizontally stratified formation of variable porosity with a constant flux at the soil surface. Relating moments of...
Use of longitudinal strain in identifying driving and resisting elements of landslides
R.L. Baum, R. W. Fleming
1991, Geological Society of America Bulletin (103) 1121-1152
Observations of deformation at the surfaces of landslides in Utah and Hawaii indicate that the upslope parts of the land-slides have stretched and the downslope parts have shortened parallel with the direction of movement. The maximum displacement of each landslide occurs in a...
Identification of dissolved-constituent sources in mine-site ground water using batch mixing
Gregory M. Clark, Robert S. Williams Jr.
1991, Water Resources Bulletin (27) 93-100
Batch-mixing experiments were used to help identify lithologic and mineralogic sources of increased concentrations of dissolved solids in water affected by surface coal mining in northwestern Colorado. Ten overburden core samples were analyzed for mineral composition and mixed with distilled water for 90 days until mineral-water equilibrium was reached. Between...
Periphyton accumulation at remote reefs and shoals in Lake Superior
Thomas A. Edsall, Eugene F. Stoermer, John P. Kociolek
1991, Journal of Great Lakes Research (17) 412-418
Observations made from a submarine showed that the bed-rock surfaces at water depths of about 5 to 14 m on Stannard Rock and Superior Shoal in Lake Superior were covered with a dense, fleece-like blanket of periphyton. Examination of the periphyton revealed it consisted primarily of structurally complex, diverse, diatom...
Prey selection for the exotic cladoceran Bythotrephes cederstroemi by selected Lake Erie fishes
Michael T. Bur, David M. Klarer
1991, Journal of Great Lakes Research (17) 85-93
The importance of zooplankton in the diet of yellow perch (Perca flavescens), white perch (Morone americana), walleyes (Stizostedion vitreum vitreum), and white bass (M. chry-sops)was assessed in the central basin of Lake Erie in 1985–1988. Zooplankton were collected by vertical hauls in 1987–1988 and fish with a rock-hopper trawl. Although...