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Page 4844, results 121076 - 121100

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Chemistry and isotope ratios of sulfur in basalts and volcanic gases at Kilauea volcano, Hawaii
H. Sakai, T. J. Casadevall, J.G. Moore
1982, Geochimica et Cosmochimica Acta (46) 729-738
Eighteen basalts and some volcanic gases from the submarine and subaerial parts of Kilauea volcano were analyzed for the concentration and isotope ratios of sulfur. By means of a newly developed technique, sulfide and sulfate sulfur in the basalts were separately but simultaneously determined. The submarine basalt has 700 ±...
Siderite concretions: indicators of early diagenesis in the Gammon shale (Cretaceous).
D. L. Gautier
1982, Journal of Sedimentary Petrology (52) 859-871
The Gammon member of the Pierre shale of the northern Great Plains, USA, contains abundant siderite concretions. The relative depth and time of siderite precipitation can be inferred from the structure, mineralogy and isotopic composition of these concretions. Concretions that formed at shallow depths, early in the history of the...
Environmental implications of test-to-substrate attachment among some modern sublittoral foraminifera
C. Wylie Poag
1982, Geological Society of America Bulletin (93) 252-268
Topographic highs on the outer continental shelf of New Jersey are sites for the concentration of three species of attached calcareous benthic foraminifera. Elphidium subarcticum Cushman, normally considered a vagrant species, cements itself by an organic film to one or more quartz grains. Webbinella concave (Williamson) attaches to quartz grains...
The chemical and isotopic record of rock-water interaction in the Sherman Granite, Wyoming and Colorado
R. A. Zielinski, Z. E. Peterman, J. S. Stuckless, J.N. Rosholt, Ignatius T. Nkomo
1982, Contributions to Mineralogy and Petrology (78) 209-219
Chemical, isotopic, radiographic, and rock-leaching data are combined to describe the effects of rock-water interactions in core samples of petrographically fresh, 1.43 b.y.-old Sherman Granite. The data serve to identify sensitive indicators of incipient alteration and to estimate the degree, pathways, and timing of element mobilization. Unfractured core samples of...
Chemical and isotopic diversity in basalts dredged from the East Pacific Rise at 10°S, the fossil Galapagos Rise and the Nazca plate
Rodey Batiza, Richard Oestrike, Kiyoto Futa
1982, Marine Geology (49) 115-132
We present petrographic, chemical and isotopic data for fresh lava samples dredged from three regions: (1) the fossil Galapagos Rise; (2) an elongate volcano near this extinct spreading center; and (3) the East Pacific Rise at 10°S. The samples from the Galapagos Rise are among the first samples from...
A quantitative index of soil development from field descriptions: Examples from a chronosequence in central California
J.W. Harden
1982, Geoderma (28) 1-28
A soil development index has been developed in order to quantitatively measure the degree of soil profile development. This index, which combines eight soil field properties with soil thickness, is designed from field descriptions of the Merced River chronosequence in central California. These eight properties are: clay films, texture plus...
The mobility of uranium and other elements during alteration of rhyolite ash to montmorillonite: A case study in the Troublesome Formation, Colorado, U.S.A.
R. A. Zielinski
1982, Chemical Geology (35) 185-204
An unusual occurrence of juxtaposed glassy and clay-altered ash was sampled to estimate the degree and type of element mobility during alteration of glass to montmorillonite. The results are particularly interesting in that major mobilization of uranium is indicated. Closely spaced samples of glassy and montmorillonitic ash were collected from...
Hydrologic inferences from ring widths of flood-damaged trees, Potomac River, Maryland
T.M. Yanosky
1982, Environmental Geology (4) 43-52
Year-to-year variability in the ring widths of trees on flood plains along two reaches of the Potomac River near Washington, D.C., seems in large part to be related to differences in flood-flow regimes. Trees directly exposed to high flood velocities are damaged more often than sheltered trees and thus exhibit...
13C Nuclear magnetic resonance studies of kerogen from Cretaceous black shales thermally altered by basaltic intrusions and laboratory simulations
L.W. Dennis, G.E. Maciel, Patrick G. Hatcher, Bernd R. T. Simoneit
1982, Geochimica et Cosmochimica Acta (46) 901-907
Cretaceous black shales from DSDP Leg 41, Site 368 in the Eastern Atlantic Ocean were thermally altered during the Miocene by an intrusive basalt. The sediments overlying and underlying the intrusive body were subjected to high temperatures (up to ~ 500°C) and, as a result, their kerogen was significantly altered....
Velocity and bottom-stress measurements in the bottom boundary layer, outer Norton Sound, Alaska.
D.A. Cacchione, D.E. Drake, P. Wiberg
1982, Geologie en Mijnbouw (61) 71-78
We have used long-term measurements of near-bottom velocities at four heights above the sea floor in Norton Sound, Alaska, to compute hourly values of shear velocity u., roughness and bottom-drag coefficient. Maximum sediment resuspension and transport, predicted for periods when the computed value of u. exceeds a critical level, occur...
Aminostratigraphy and faunal correlations of late Quaternary marine terraces, Pacific Coast, USA
G. L. Kennedy, K. R. Lajoie, J.F. Wehmiller
1982, Nature (299) 545-547
Recent studies using the extent of racemization of amino acids to date fossil mollusc shells in the Arctic1, the British Isles2 and on the Atlantic3,4 and Pacific5-13 coasts of North America have relied mainly on theoretical kinetic models of racemization. Ages generated in this fashion are highly model dependent and...
Geochemistry of a Pliocene-Pleistocene oceanic-arc plutonic complex, Guadalcanal
A.R. Chivas, A.S. Andrew, A.K. Sinha, J. R. O’Neil
1982, Nature (300) 139-143
The Koloula Igneous Complex, on the island of Guadalcanal, consists of a low-K calc-alkaline sequence of 26 different intrusive phases. The major intrusions are characterized by K/Rb>400, Rb/Sr<0.06, ?? 18O of 5.7 to 7.2 and uniform 87Sr/86Sr of 0.70372. This article presents the first data describing oxygen and strontium isotopic...
Origin and distribution of tonsteins in late permian coal seams of Southwestern China
Yinzhu Zhou, Y.-L. Ren, B.F. Bohor
1982, International Journal of Coal Geology (2) 49-77
We have surveyed the areal and stratigraphic distribution of tonsteins in Late Permian coalfields of southwestern China over an area of several hundred thousand square kilometers. We studied the relationship between tonstein distribution and sedimentary environment. Based on mineralogical and...
Leaching of radionuclides from uranium ore and mill tailings ( Ra- 226, Tn-230).
E. R. Landa
1982, Uranium (1) 53-63
The major part of the extractable uranium is associated with a readily acid-soluble fraction in both ore and tailings. The major part of the extractable 226Ra was associated with an iron, manganese hydrous-oxide fraction in the ore and tailings. Thorium-230 was the least leachable of the radionuclides studied. The major...
Introduction: seismology and earthquake engineering in Mexico and Central and South America.
A. F. Espinosa
1982, Earthquake Information Bulletin (USGS) (14) 4-6
The results from seismological studies that are used by the engineering community are just one of the benefits obtained from research aimed at mitigating the earthquake hazard. In this issue of Earthquake Information Bulletin current programs in seismology and earthquake engineering, seismic networks, future plans and some of the cooperative...
Bank stability and channel width adjustment, East Fork River, Wyoming
E.D. Andrews
1982, Water Resources Research (18) 1184-1192
Frequent surveys of eight cross sections located in self-formed reaches of the East Fork River, Wyoming, during the 1974 snowmelt flood showed a close relation between channel morphology and scour and fill. Those cross sections narrower than the mean reach width filled at discharges less than bankfull and scoured at...
Stolzite from Tsumeb.
E.E. Foord, N. M. Conklin
1982, Mineralogical Record (13) 149-150
The world's largest known crystal of stolzite (1.3 X 1.3 X 2.5 cm) is described. It is associated with tennantite and quartz, and is from the Tsumeb mine, Tsumeb, Namibia. Forms present include (001), (111), (101), (122), and (212). Spectrographic analyses indicate a nearly end-member composition with Mo, Fe, Ba,...
Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry
A. L. Meier
1982, Analytical Chemistry (54) 2158-2161
The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe...
Cretaceous biostratigraphy in the Wyoming thrust belt.
D. J. Nichols, S.R. Jacobson
1982, Mountain Geologist (19) 73-78
In the Cretaceous section of the thrust belt, fossils are especially useful for dating and correlating repetitive facies of different ages in structurally complex terrain. The biostratigraphic zonation for the region is based on megafossils (chiefly ammonites) , which permit accurate dating and correlation of outcrop sections, and which have...
Space platform albedo measurements as indicators of change in arid lands
C.J. Robinove
1982, Advances in Space Research (2) 31-35
The change in albedo of arid lands is an indicator of changes in their condition and quality, including density of vegetative cover, erosion, deposition, surficial soil moisture, and man-made change. In general, darkening of an arid land surface indicates an increase in land quality while brightening indicates a decrease in...
An improved method for the determination of trace levels of arsenic and antimony in geological materials by automated hydride generation–Atomic absorption spectroscopy
J.G. Crock, F.E. Lichte
1982, Analytica Chimica Acta (144) 223-233
An improved, automated method for the determination of arsenic and antimony in geological materials is described. After digestion of the material in sulfuric, nitric, hydrofluoric and perchloric acids, a hydrochloric acid solution of the sample is automatically mixed with reducing agents, acidified with additional hydrochloric acid, and treated with a...
Landsat monitoring of desert vegetation growth, 1972-1979 using a plant-shadowing model
Joseph Otterman, C.J. Robinove
1982, Advances in Space Research (2) 45-50
Landsat digital data spanning the period 1972-1979 were analyzed to monitor the status of vegetation within and outside an exclosure in the northern Sinai (precipitation 100-150 mm/year). This 6??6 km exclosure was fenced off in the summer of 1974 and subsequently has been free from the anthropogenic pressures (overgrazing, cultivation...