Pb, Sr, Nd, and Hf isotopic constraints on the origin of Hawaiian basalts and evidence for a unique mantle source
P. Stille, D.M. Unruh, M. Tatsumoto
1986, Geochimica et Cosmochimica Acta (50) 2303-2319
Pb, Sr, Nd, and Hf isotopic relationships among basalts from the Hawaiian Islands suggest that these basalts were derived from three sources; the oceanic lithosphere (Kea end member), the depleted asthenosphere (posterosional end member) and a deep-mantle plume (Koolau end member).Hawaiian tholeiites are derived within the lithosphere and the isotopic...
Secretinite: A proposed new maceral of the inertinite maceral group
P.C. Lyons, Patrick G. Hatcher, F. W. Brown
1986, Fuel (65) 1094-1098
The new maceral secritinite (name derived from the word ‘secretory’) is proposed for subcircular, ovoid, crescent-shaped or oblong, commonly round on one or more sides, noncellular, highly reflective components of the inertinite maceral group. This maceral of secretory origin, known from many bituminous coals throughout the world, has been confused...
Internal structural variations in a debris-avalanche deposit from ancestral Mount Shasta, California, USA
T. Ui, H. Glicken
1986, Bulletin of Volcanology (48) 189-194
Various parameters of the internal structure of a debris-avalanche deposit from ancestral Mount Shasta (size and percentage of block facies in each exposure, number and width of jigsaw cracks, and number of rounded clasts in matrix facies) were measured in order to study flow and emplacement mechanisms. Three types of...
Oxygen isotope compositions of selected laramide-tertiary granitoid stocks in the Colorado Mineral Belt and their bearing on the origin of climax-type granite-molybdenum systems
J. L. Hannah, H. J. Stein
1986, Contributions to Mineralogy and Petrology (93) 347-358
Quartz phenocrysts from 31 granitoid stocks in the Colorado Mineral Belt yield ??18O values less than 10.4???, with most values between 9.3 and 10.4???. An average magmatic value of about 8.5??? is suggested. The stocks resemble A-type granites; these data support magma genesis by partial melting of previously depleted, fluorine-enriched,...
The problem of complex eigensystems in the semianalytical solution for advancement of time in solute transport simulations: a new method using real arithmetic
Amjad M.J. Umari, Steven M. Gorelick
1986, Water Resources Research (22) 1149-1154
In the numerical modeling of groundwater solute transport, explicit solutions may be obtained for the concentration field at any future time without computing concentrations at intermediate times. The spatial variables are discretized and time is left continuous in the governing differential equation. These semianalytical solutions have been presented in the...
Precision of a field method for determination of pH in dilute lakes
J.T. Turk
1986, Water, Air, & Soil Pollution (27) 237-242
Replicate pH measurements in three dilute lakes made during extreme conditions indicate that pH can be measured in the field with a variance due to measurement error of 0.005 unit. Error of the field technique in measuring the pH of dilute solutions in the laboratory ranges from less than 0.01...
The evolution of young silicic lavas at Medicine Lake Volcano, California: Implications for the origin of compositional gaps in calc-alkaline series lavas
T.L. Grove, J.M. Donnelly-Nolan
1986, Contributions to Mineralogy and Petrology (92) 281-302
At Medicine Lake Volcano, California, the compositional gap between andesite (57-62 wt.% SiO2) and rhyolite (73-74 wt.% SiO2) has been generated by fractional crystallization. Assimilation of silicic crust has also occurred along with fractionation. Two varieties of inclusions found in Holocene rhyolite flows, hornblende gabbros and aphyric andesites, provide information...
Paleodrainages of the Eastern Sahara-The radar rivers revisited (SIR-A/B Implications for a Mid-Tertiary Trans-Afnrcan Drainage System)
John F. McCauley, Carlos S. Breed, Gerald G. Schaber, William P. McHugh, Bahay Issawi, C. Vance Haynes, Maurice J. Grolier, Ali El Kilani
1986, IEEE Transactions on Geoscience and Remote Sensing (GE-24) 624-648
A complex history of Cenozoic fluvial activity in the presently hyperarid Eastern Sahara is inferred from SIR data and postflight field investigations in southwest Egypt and northwest Sudan. SIR images were coregistered with Landsat and existing maps as a guide to exploration of the buried paleodrainages (radar rivers) first discovered...
Modern alluvial history of the Paria Rver drainage basin, southern Utah
R. Hereford
1986, Quaternary Research (25) 293-311
Stream channels in the Paria River basin were eroded and partially refilled between 1883 and 1980. Basin-wide erosion began in 1883; channels were fully entrenched and widened by 1890. This erosion occurred during the well-documented period of arroyo cutting in the Southwest. Photographs of the Paria River channel taken between...
A tubular-coring device for use in biogeochemical sampling of succulent and pulpy plants
W. L. Campbell
1986, Journal of Geochemical Exploration (25) 397-399
A hand-operated, tubular-coring device developed for use in biogeochemical sampling of succulent and pulpy plants is described. The sampler weighs about 500 g (1.1 lb); and if 25 × 175 mm (1 × 7 in) screw-top test tubes are used as...
Effects of temperature and sliding rate on frictional strength of granite
D.A. Lockner, R. Summers, J.D. Byerlee
1986, Pure and Applied Geophysics PAGEOPH (124) 445-469
Layers of artificial granite gouge have been deformed on saw-cut granite surfaces inclined 30?? to the sample axes. Samples were deformed at a constant confining pressure of 250 MPa and temperatures of 22 to 845??C. The velocity dependence of the steady-state coefficient of friction (??ss) was determined by comparing sliding...
Stick slip, charge separation and decay
D.A. Lockner, J.D. Byerlee, V.S. Kuksenko, A.V. Ponomarev
1986, Pure and Applied Geophysics PAGEOPH (124) 601-608
Measurements of charge separation in rock during stable and unstable deformation give unexpectedly large decay times of 50 sec. Time-domain induced polarization experiments on wet and dry rocks give similar decay times and suggest that the same decay mechanisms operate in the induced polarization response as in the relaxation of...
CHARACTERIZATION OF SANDSTONE RESERVOIRS FOR ENHANCED OIL RECOVERY: THE PERMIAN UPPER MINNELUSA FORMATION, POWDER RIVER BASIN, WYOMING.
Christopher J. Schenk, J. W. Schmoker, J.M. Scheffler
1986, Conference Paper, Society of Petroleum Engineers of AIME, (Paper) SPE
Upper Minnelusa sandstones form a complex group of reservoirs because of variations in regional setting, sedimentology, and diagenetic alteration. Structural lineaments separate the reservoirs into northern and southern zones. Production in the north is from a single pay sand, and in the south from multi-pay sands due to differential erosion...
The effects of sliding velocity on the frictional and physical properties of heated fault gouge
Diane E. Moore, R. Summers, J.D. Byerlee
1986, Pure and Applied Geophysics PAGEOPH (124) 31-52
The frictional properties of a crushed granite gouge and of gouges rich in montmorillonite, illite, and serpentine minerals have been investigated at temperatures as high as 600??C, confining pressures as high as 2.5 kbar, a pore pressure of 30 bar, and sliding velocities of 4.8 and 4.8??10-2 ??m/sec. The gouges...
The modification of an estuary
F.H. Nichols, James E. Cloern, Samuel N. Luoma, D. H. Peterson
1986, Science (231) 567-573
The San Francisco Bay estuary has been rapidly modified by human activity. Diking and filling of most of its wetlands have eliminated habitats for fish and waterfowl; the introduction of exotic species has transformed the composition of its aquatic communities; reduction of freshwater inflow by more than half has changed...
A finite element model for tidal and residual circulation
Roy A. Walters
1986, Communications in Numerical Methods in Engineering (2) 393-398
Harmonic decomposition is applied to the shallow water equations, thereby creating a system of equations for the amplitude of the various tidal constituents and for the residual motions. The resulting equations are elliptic in nature, are well posed and in practice are shown to be numerically well-behaved. There are a...
Low-temperature heat capacity of diopside glass (CaMgSi2O6): A calorimetric test of the configurational-entropy theory applied to the viscosity of liquid silicates
P. Richet, R. A. Robie, B. S. Hemingway
1986, Geochimica et Cosmochimica Acta (50) 1521-1533
Heat-capacity measurements have been made between 8 and 370 K on an annealed and a rapidly quenched diopside glass. Between 15 and 200 K, Cp does not depend significantly on the thermal history of the glass. Below 15 K Cp is larger for the quenched than for the annealed specimen. The opposite is true...
Geology of the peralkaline volcano at Pantelleria, Strait of Sicily
G.A. Mahood, W. Hildreth
1986, Bulletin of Volcanology (48) 143-172
Situated in a submerged continental rift, Pantelleria is a volcanic island with a subaerial eruptive history longer than 300 Ka. Its eruptive behavior, edifice morphologies, and complex, multiunit geologic history are representative of strongly peralkaline centers. It is dominated by the 6-km-wide Cinque Denti caldera, which formed ca. 45 Ka...
Detection of erosion events using 10Be profiles: example of the impact of agriculture on soil erosion in the Chesapeake Bay area (U.S.A.)
J. N. Valette-Silver, L. Brown, M. Pavich, J. Klein, R. Middleton
1986, Earth and Planetary Science Letters (80) 82-90
10Be concentration, total carbon and grain-size were measured in cores collected in undisturbed estuarine sediments of three tributaries of the Chesapeake Bay. These cores were previously studied by Davis [1] and Brush [2,3] for pollen content, age and sedimentation rate. In this work, we compare the results obtained for these...
Isotope geochemistry of recent magmatism in the Aegean arc: Sr, Nd, Hf, and O isotopic ratios in the lavas of Milos and Santorini-geodynamic implications
L. Briqueu, M. Javoy, J.R. Lancelot, M. Tatsumoto
1986, Earth and Planetary Science Letters (80) 41-54
In this comparative study of variations in the isotopic compositions (Sr, Nd, O and Hf) of the calc-alkaline magmas of the largest two volcanoes, Milos and Santorini, of the Aegean arc (eastern Mediterranean) we demonstrate the complexity of the processes governing the evolution of the magmas on the scale both...
Mars: A water-rich planet?
M. H. Carr
1986, Icarus (68) 187-216
Mars had outgassed at least 0.5 to 1 km of water, 10 to 20 bar of CO2, and 0.1 to 0.3 bar of N2. The volatiles that have been retained are mostly in the cratered uplands. Terrain softening, fretted channels, debris...
Pb-, Sr- and Nd-Isotopic systematics and chemical characteristics of cenozoic basalts, Eastern China
Z. C. Peng, R. E. Zartman, K. Futa, D.G. Chen
1986, Chemical Geology (59) 3-33
Forty-eight Paleogene, Neogene and Quaternary basaltic rocks from northeastern and east-central China have been analyzed for major-element composition, selected trace-element contents, and Pb, Sr and Nd isotopic systematics. The study area lies entirely within the marginal Pacific tectonic domain. Proceeding east to...
SALTWATER INTRUSION IN A HIGHLY TRANSMISSIVE UNCONFINED AQUIFER.
Bradley G. Waller
1986, Conference Paper
Saltwater intrusion is particularly dynamic in coastal Dade County because of the high permeability of the Biscayne aquifer, because of the good interconnection between canals and the aquifer, and because of the seasonal rainfall. The problem is accentuated as urban growth continues to encroach on inland wetland areas which results...
EVIDENCE FOR THREE MODERATE TO LARGE PREHISTORIC HOLOCENE EARTHQUAKES NEAR CHARLESTON, S. C.
Robert E. Weems, Stephen F. Obermeier, Milan J. Pavich, Gregory S. Gohn, Meyer Rubin, Richard L. Phipps, Robert B. Jacobson
1986, Conference Paper
Earthquake-induced liquefaction features (sand blows), found near Hollywood, S. C. , have yielded abundant clasts of humate-impregnated sand and sparse pieces of wood. Radiocarbon ages for the humate and wood provide sufficient control on the timing of the earthquakes that produced the sand blows to indicate that at least three...
An interpretation of induced electric currents in long pipelines caused by natural geomagnetic sources of the upper atmosphere
W.H. Campbell
1986, Surveys in Geophysics (8) 239-259
Electric currents in long pipelines can contribute to corrosion effects that limit the pipe's lifetime. One cause of such electric currents is the geomagnetic field variations that have sources in the Earth's upper atmosphere. Knowledge of the general behavior of the sources allows a prediction of the occurrence times, favorable...
