Lu-Hf total-rock age for the Amîtsoq gneisses, West Greenland
H.S. Pettingill, P. J. Patchett
1981, Earth and Planetary Science Letters (55) 150-156
Lu-Hf total-rock data for the Amîtsoq gneisses of West Greenland yield an age of 3.55±0.22Gy(2σ), based on the decay constant λ176Lu=1.96×10−11y−1, and an initial176Hf/177Hf ratio of 0.280482±33. The result is in good agreement with Rb-Sr total-rock and U-Pb zircon ages. In spite of severe metamorphism of the area at 2.9...
Minor and trace element geochemistry of volcanic rocks dredged from the Galapagos spreading center: Role of crystal fractionation and mantle heterogeneity
D.A. Clague, F.A. Frey, G. Thompson, S. Rindge
1981, Journal of Geophysical Research Solid Earth (86) 9469-9482
A wide range of rock types (abyssal tholeiite, Fe-Ti-rich basalt, andesite, and rhyodacite) were dredged from near 95°W and 85°W on the Galapagos spreading center. Computer modeling of major element compositions has shown that these rocks could be derived from common parental magmas by successive degrees of fractional crystallization. However,...
Halogenated benzene radical cations and ground state degeneracy splitting by asymmetric substitution
V.E. Bondybey, C.R. Vaughn, T.A. Miller, J.H. English, R.H. Shiley
1981, Journal of Chemical Physics (74) 6584-6591
The absorption and laser induced fluorescence of several halogenated benzene radical cations were studied in solid Ne matrices. The spectra of 1,2,4-trifluorobenzene, l,3-dichloro-5-fluorobenzene, and l-chloro-3,5- difluorobenzene radical cations are observed and analyzed. Studies of fluorescence polarization and a photoselection technique were used to examine the splitting of the degeneracy of...
Origin and structural implications of upper Miocene rhyolites in Kingston Canyon, Piute County, Utah
P. D. Rowley, T. A. Steven, H. H. Mehnert
1981, Geological Society of America Bulletin (92) 590-602
Kingston Canyon is one of the deepest antecedent canyons in the High Plateaus subprovince of the Colorado Plateaus. Here the East Fork of the Sevier River flows westward transversely across the gently east tilted Sevier Plateau, which is developed on a basin-range fault...
Late Cenozoic stages and molluscan zones of the U.S. Middle Atlantic Coastal Plain
B. W. Blackwelder
1981, Journal of Paleontology, Supplement, Part II (55)
Pliocene to Holocene deposits of the U.S.Atlantic Coastal Plain from Maryland to Georgia are divided into four stages and four substages using molluscan biostratigraphic data. These divisions are the Wiltonian and Burwellian Stages (early Pliocene), Gouldian and Windyan Substages of the Colerainian Stage (late Pliocene to early Pleistocene), and Myrtlean...
Geological opportunities and constraints on the use of underground space
M.S. Walton
1981, Underground Space (5) 287-289
[No abstract available]...
A distribution-free alternative to least-squares regression and its application to Rb/Sr isochron calculations
R.G. Vugrinovich
1981, Journal of the International Association for Mathematical Geology (13) 443-454
A distribution-free estimator of the slope of a regression line is introduced. This estimator is designated Sm and is given by the median of the set of n(n - 1)/2 slope estimators, which may be calculated by inserting pairs of points (Xi, Yi)and (Xj, Yj)into the slope formula Si =...
The relationship of geophysical measurements to hydraulic conductivity at the Brantley damsite, New Mexico
U. Schimschal
1981, Geoexploration (19) 115-125
The objective of this study was to develop techniques to correlate hydraulic conductivity tests with geophysical logs. In addition, the relationships obtained from boreholes were correlated to surface resistivity soundings in an effort to define areas of potential high water loss at the proposed site for Brantley Dam.Hydraulic conductivity obtained...
The origin and isotopic composition of dissolved sulfide in groundwater from carbonate aquifers in Florida and Texas
R. O. Rye, W. Back, B.B. Hanshaw, C.T. Rightmire, F. J. Pearson Jr.
1981, Geochimica et Cosmochimica Acta (45) 1941-1950
The δ34S values of dissolved sulfide and the sulfur isotope fractionations between dissolved sulfide and sulfate species in Floridan ground water generally correlate with dissolved sulfate concentrations which are related to flow patterns and residence time within the aquifer. The dissolved sulfide derives from the slow in situ biogenic reduction of sulfate dissolved from...
Response of the suspended sediment transport system to continental shelf dynamics
Herman A. Karl, D.E. Drake, D.A. Cacchione
1981, Geo-Marine Letters (1) 243-248
Surface currents influenced by a wind-driven upwelling event in San Pedro Bay moved total suspended matter (TSM) confined to the inner shelf on 19 April 1978 seaward, so that by 27 April surface TSM had increased over the outer shelf. Near-bottom concentrations of TSM also increased across the shelf during...
Plate-tectonic mechanism of Laramide deformation.
W. Hamilton
1981, Contributions to Geology - University of Wyoming, Laramie (19) 87-92
The Laramide compressive deformation of the craton was caused by a clockwise rotation of about 2-4o of the Colorado Plateau region relative to the continental interior, during late Late Cretaceous and early Tertiary time. Late Paleozoic and Neogene deformation of the craton also were produced by motion of a southwestern...
East Pacific rise at 21°N: the volcanic, tectonic, and hydrothermal processes of the central axis
Richard D. Ballard, Jean Francheteau, Tierre Juteau, Claude Rangan, William Normark
1981, Earth and Planetary Science Letters (55) 1-10
Photographs obtained by the ANGUS survey system at 21°N reveal many similarities to the geological processes delineated at other spreading centers and in particular those observed in the Galapagos Rift at 86°W. The region of recent volcanism is restricted to a narrow zone (Zone 1) approximately 1 km wide. This...
Late Cenzoic rhyolites from the Kern Plateau, southern Sierra Nevada, California.
C. R. Bacon, W. A. Duffield
1981, American Journal of Science (281) 1-34
Four late Cenozoic rhyolite domes lie atop the Kern Plateau, 30 to 40km S-SE of Mount Whitney. K-Ar and 40Ar/39Ar dating shows that Monache, Templeton, and Little Templeton Mountains are all about 2.4Ma old; a small dome nearby is approx 0.2Ma old. The three older rhyolites have SiO2 = 73-74%...
Faulting in outer continental shelf of southern Bering Sea
James V. Gardner, Tracy L. Vallier
1981, American Association of Petroleum Geologists Bulletin (65) 1568-1573
Synthesis of more than 10 000 line-km of high-resolution seismic data indicates the distribution, types, and trends of faults present on the outer continental shelf of the southern Bering Sea. Faults are classified into three types as to whether they 1) offset the sea floor (surface fault), 2) show less...
Hydrologic testing of tight zones in southeastern New Mexico
K.F. Dennehy, P. A. Davis
1981, Groundwater (19) 482-489
Increased attention is being directed toward the investigation of tight zones in relation to the storage and disposal of hazardous wastes. Shut-in tests, slug tests, and pressure-slug tests are being used at the proposed Waste Isolation Pilot Plant site, located in southeastern New Mexico, to...
Historical review of and current progress in coal-resource estimation in the United States
G.H. Wood Jr.
1981, Geological Society of America Bulletin (92) 520-528
Nine estimates of the coal resources of the United States have been published in the past 71 years. Although many details of these estimates differ markedly, the 1913, 1922, and 1974 estimates are surprisingly similar. Some differences are due to increased geologic data,...
Objectives, accomplishments, and future plans of IGCP project 143, remote sensing and mineral exploration
W. D. Carter, L. C. Rowan
1981, Advances in Space Research (1) 227-236
The International Geological Correlation Programme (IGCP) is a worldwide cooperative research programme that began in 1974 under the auspices of the International Union of Geological Sciences. Because of the global availability of Earth resources data collected by satellites and the great interest among geologists in taking advantage of these new...
Preconsolidation stress of aquifer systems in areas of induced land subsidence
Thomas L. Holzer
1981, Water Resources Research (17) 693-704
Aquifer systems in the Eloy-Picacho area, Arizona, the Houston-Galveston area, Texas, and the Tulare-Wasco area and Santa Clara Valley, California, appear to have been overconsolidated by an amount that ranged approximately from 1.6 to 6.2 bars (16 to 63 m of water) before man began to withdraw groundwater from them....
Measurement and computation of bed-material discharge in a shallow sand-bed stream, Muddy Creek, Wyoming
E.D. Andrews
1981, Water Resources Research (17) 131-141
Both the measurement and computation of the bed-material discharge of a stream involve large uncertainties because of the difficulties in determining bedload discharge. Measurements of bedload discharge are rare and frequently of unknown accuracy because no bedload sampler has been extensively tested and calibrated over a wide range of hydraulic...
Gas hydrates (clathrates) causing pore-water freshening and oxygen isotope fractionation in deep-water sedimentary sections of terrigenous continental margins
R. Hesse, W.E. Harrison
1981, Earth and Planetary Science Letters (55) 453-462
The occurrence of gas hydrates in deep-water sections of the continental margins predicted from anomalous acoustic reflectors on seismic profiles has been confirmed by recent deep-sea drilling results. On the Pacific continental slope off Guatemala gas hydrates were brought up for...
Interaction between diapirism and sediment loading at the shelf-slope boundary, northwest Gulf of Mexico
A. R. Trippet
1981, Geo-Marine Letters (1) 111-114
During the last low stand of sea level, rivers and streams drained across the present northwestern Gulf of Mexico continental shelf depositing sediments in several shallow-water deltas near the present shelf-slope boundary. The weight of these wedges of prograded sediments triggered or augmented both subsidence of local depositional basins and...
Morphology and processes associated with the accumulation of the fine-grained sediment deposit on the southern New England shelf
David C. Twichell, Charles E. McClennen, Bradford Butman
1981, Journal of Sedimentary Petrology (51) 269-280
A 13,000 km2 area of the southern New England Continental Shelf which is covered by anomalously fine-grained sediment has been surveyed by means of high-resolution, seismic-reflection and side-scan sonar techniques to map its morphology and structure, and a near-bottom instrument system contributed to understanding present activity of the deposit. Seismic-reflection...
A numerical inversion of the Laplace transform solution to radial dispersion in a porous medium
A.F. Moench, A. Ogata
1981, Water Resources Research (17) 250-252
A special form of the numerical inversion of the Laplace transform described by Stehfest (1970) is applied to the transformed solution of dispersion in a radial flow system in a porous medium. The inversion is extremely simple to use because the weighting coefficients depend only on the number of terms...
The Redskin granite: Evidence for thermogravitational diffusion in a Precambrian granite batholith
S. Ludington
1981, Journal of Geophysical Research Solid Earth (86) 10423-10430
The 1000-Ma-old composite Pikes Peak batholith consists largely of medium- to coarse-grained biotite granite but is intruded by several smaller granite plutons. Two of these, the Tarryall Mountains batholith and the Redskin Granite (Hawley, 1969; Hawley and Wobus, 1977), are here interpreted as cupolas atop the main mass of the...
Geochemical prospecting for hydrocarbons in the outer continental shelf, Southern Bering Sea, Alaska
K.A. Kvenvolden, T.M. Vogel, J.V. Gardner
1981, Journal of Geochemical Exploration (14) 209-219
This geochemical survey is based on 20 stations located on the outer continental shelf of the southern Bering Sea in an area of 30,000 km2 that includes St. George basin. Hydrocarbon gases from sediment samples recovered by gravity coring at each of the stations were analyzed by gas chromatography. Data are...
