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 =...
Geodetic strain measurements in Washington
J.C. Savage, M. Lisowski, W.H. Prescott
1981, Journal of Geophysical Research Solid Earth (86) 4929-4940
Two new geodetic measurements of strain accumulation in the state of Washington for the interval 1972–1979 are reported. Near Seattle the average principal strain rates are 0.07 ± 0.03 μstrain/yr N 19°W and −0.13 ± 0.02 μstrain/yr N71°E, and near Richland (south central Washington) the average principal strain rates are...
On the use of the nephelometer in estuarine waters
A. Eaton, V. Grant, O. Bricker, D. Wells
1981, Estuaries (4) 379-384
A study of the problems encountered in nephelometric determinations of suspended sediment loads in the Chesapeake Bay estuary has led to development of a technique which uses nephelometer readings as a guide for sampling at vertical profiles in an estuary. This permits optimum sampling for concentration profiles and allows one...
Coincident sediment slump/clathrate complexes on the U.S. Atlantic continental slope
G. Carpenter
1981, Geo-Marine Letters (1) 29-32
High-resolution seismic reflection data recorded on the continental slope off the east coast of the United States have revealed instances of sediment mass movement (slumps) which appear to occur above clathrate accumulations. The slumping is believed to be related to the liberation of free gas by clathrate decomposition and consequent...
Oxygen isotope thermometry of basic lavas and mantle nodules
T.K. Kyser, J. R. O’Neil, I. S. E. Carmichael
1981, Contributions to Mineralogy and Petrology (77) 11-23
Measurements have been made of the oxygen isotope and chemical composition of glass and phenocrysts in lavas and coexisting minerals in mantle nodules. Temperatures of formation of these assemblages have been estimated from various chemical thermometers and range from 855?? to 1,300?? C. The permil fractionations between coexisting orthopyroxene and...
Chemical composition, stratigraphy, and depositional environments of the Black River Group (Middle Ordovician), southwestern Ohio.
David A. Stith
1981, Geological Society of America Bulletin (92) 629-633
The chemical composition and stratigraphy of the Black River Group in southwestern Ohio were studied. Chemical analyses were done on two cores of the Black River from Adams and Brown Counties, Ohio. These studies show that substantial reserves of high-carbonate rock are present in the Black River at depths of...
Estimation of surface temperature variations due to changes in sky and solar flux with elevation
S. Hummer-Miller
1981, Geophysical Research Letters (8) 595-598
Sky and solar radiance are of major importance in determining the ground temperature. Knowledge of their behavior is a fundamental part of surface temperature models. These two fluxes vary with elevation and this variation produces temperature changes. Therefore, when using thermal-property differences to discriminate geologic materials,...
Sudden death at the end of the Mesozoic
C. Emiliani, E.B. Kraus, E.M. Shoemaker
1981, Earth and Planetary Science Letters (55) 317-334
A paleoecological analysis of the fossil record before and after the Cretaceous/Tertiary boundary indicates that the widespread extinctions and biological stresses around the boundary are best explained in terms of a sudden, significant, but short temperature rise. L. Alvarez and co-authors, having...
Rates of manganese oxidation in aqueous systems
J.D. Hem
1981, Geochimica et Cosmochimica Acta (45) 1369-1374
The rate of crystal growth of Mn3O4 (hausmannite) and βMnOOH (feitknechtite) in aerated aqueous manganous perchlorate systems, near 0.01 M in total manganese, was determined at pH levels ranging from 7.00 to 9.00 and at temperatures from 0.5 to 37.4°C. The process is autocatalytic, but becomes psuedo first-order in dissolved Mn2+ activity...
Seismic amplitude anomalies associated with thick First Leo sandstone lenses, eastern Powder River basin, Wyoming
A. H. Balch, Myung W. Lee, J. J. Miller, R. T. Ryder
1981, Geophysics (46) 1519-1527
Several new discoveries of oil production in the Leo sandstone, an economic unit in the Pennsylvanian middle member of the Minnelusa formation, eastern Powder River basin, Wyoming-Nebraska-South Dakota, have renewed exploration interest in this area. Vertical seismic profiles (VSP) and model studies suggested that a measurable seismic amplitude anomaly is...
A five-collector system for the simultaneous measurement of argon isotope ratios in a static mass spectrometer
J. S. Stacey, N.D. Sherrill, G. B. Dalrymple, M. A. Lanphere, N.V. Carpenter
1981, International Journal of Mass Spectrometry and Ion Physics (39) 167-180
A system is described that utilizes five separate Faraday-cup collector assemblies, aligned along the focal plane of a mass spectrometer, to collect simultaneous argon ion beams at masses 36–40. Each collector has its own electrometer amplifier and analog-to-digital measuring channel, the outputs of which are processed by a minicomputer that...
Dating of Archean basement in northeastern Wyoming and southern Montana.
Z. E. Peterman
1981, Geological Society of America Bulletin (92) 139-146
Rb-Sr whole-rock and U-Pb zircon ages of granite and gneiss cores from three deep drill holes extend known occurrences of Archean rocks in the subsurface of NE Wyoming and S Montanta. Rb-Sr and K- Ar mineral ages are discordant and reflect early or middle Proterozoic disturbance. Highly altered rocks occur...
Discrimination of a chestnut-oak forest unit for geologic mapping by means of a principal component enhancement of Landsat multispectral scanner data
M. D. Krohn, N.M. Milton, D. Segal, A. Enland
1981, Geophysical Research Letters (8) 151-154
A principal component image enhancement has been effective in applying Landsat data to geologic mapping in a heavily forested area of eastern Virginia. A chestnut-oak forest unit, which occurs on metavolcanic rocks and some metaclastic rocks in the western Piedmont and on highly weathered upland...
Geographic distribution and dispersal of normapolles genera in North America
R.H. Tschudy
1981, Review of Palaeobotany and Palynology (35) 283-314
Normapolles pollen have been found in North America in Cretaceous and Lower Tertiary rocks from the eastern Atlantic Seaboard, the Mississippi embayment region and from the states and provinces from western North America as far north as the District of Mackenzie, Northwest Territories. Previous postulates relating to the Normapolles floral...
Fluxes of metals to a manganese nodule: Radiochemical, chemical, structural, and mineralogical studies
W.S. Moore, T.-L. Ku, J.D. Macdougall, V.M. Burns, R. Burns, J. Dymond, M.W. Lyle, D.Z. Piper
1981, Earth and Planetary Science Letters (52) 151-171
Fluxes of metals to the top and bottom surfaces of a manganese nodule were determined by combining radiochemical (230Th,231Pa,232Th,238U,234U) and detailed chemical data. The top of the nodule had been growing in its collected orientation at 4.7 mm Myr−1 for at least...
Sand waves on an epicontinental shelf: Northern Bering Sea
Michael E. Field, C. Hans Nelson, David A. Cacchione, David E. Drake
1981, Marine Geology (32) 233-258
Sand waves and current ripples occupy the crests and flanks of a series of large linear sand ridges (20 km × 5 km × 10 m high) lying in an open-marine setting in the northern Bering Sea. The sand wave area, which lies west of Seward Peninsula and southeast of...
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...
Heavy metals and manganese oxides in the genesee watershed, New York state: Effects of geology and land use
P.R. Whitney
1981, Journal of Geochemical Exploration (14) 95-117
Manganese oxide coatings on gravels from 255 sites on tributary streams in the Genesee River Watershed were analyzed for Mn, Fe, Zn, Cd, Co, Ni, Pb, and Cu. The results were compared with data on bedrock geology, surficial geology and land use, using factor analysis and stepwise multiple regression. All...
Fractionation of carbon and hydrogen isotopes by methane-oxidizing bacteria
D.D. Coleman, J.B. Risatti, M. Schoell
1981, Geochimica et Cosmochimica Acta (45) 1033-1037
Carbon isotopic analysis of methane has become a popular technique in the exploration for oil and gas because it can be used to differentiate between thermogenic and microbial gas and can sometimes be used for gas-source rock correlations. Methane-oxidizing bacteria, however,...
Geology and geochemistry of gas-charged sediment on Kodiak Shelf, Alaska
M. A. Hampton, K.A. Kvenvolden
1981, Geo-Marine Letters (1) 141-147
Methane concentrations in some sediment cores from the Kodiak Shelf and adjacent continental slope increase with depth by three or four orders of magnitude and exceed the solubility in water at ambient conditions. Acoustic anomalies in seismic-reflection records imply that methane-rich sediment is widespread. Molecular composition of hydrocarbon gases and...
Geochemical evidence for modern sediment accumulation on the continental shelf off southern New England
Michael H. Bothner, E.C. Spiker, P. P. Johnson, R.R. Rendigs, P. J. Aruscavage
1981, Journal of Sedimentary Petrology (51) 281-292
An area of fine-grained sediment approximately 170 km x 74 km in size, located in water depths between 60 m and 150 m, south of Martha's Vineyard, Mass., is a site of modern sediment deposition. The 14C ages systematically increase with sediment depth from about 1,300 years B.P. at the...
Jasperoid float and stream cobbles as tools in geochemical exploration for hydrothermal ore deposits
T.G. Lovering
1981, Journal of Geochemical Exploration (14) 69-81
Fragments of silicified rocks that are associated with deposits of base and precious metals may be transported as cobbles and pebbles in alluvium far downstream from the source outcrop. These rocks commonly exhibit certain characteristics which distinguish them from other detrital siliceous material, and may thus serve as a useful...
The partitioning of copper among selected phases of geologic media of two porphyry copper districts, Puerto Rico
R. E. Learned, T. T. Chao, R. F. Sanzolone
1981, Journal of Geochemical Exploration (15) 563-581
In experiments designed to determine the manner in which copper is partitioned among selected phases that constitute geologic media, we have applied the five-step sequential extraction procedure of Chao and Theobald to the analysis of drill core, soils, and stream sediments of the Rio Vivi and Rio Tanama porphyry copper...
Estimating usable resources from historical industry data
S.M. Cargill, D. H. Root, E. H. Bailey
1981, Economic Geology (76) 1081-1095
Historical production statistics are used to predict the quantity of remaining usable resources. The commodities considered are mercury, copper and its byproducts gold and silver, and petroleum; the production and discovery data are for the United States. The results of the study indicate that the cumulative return per unit of...
The Piney Branch Complex: A metamorphosed fragment of the central Appalachian ophiolite in northern Virginia
Avery A. Drake Jr., Benjamin A. Morgan
1981, American Journal of Science (281) 484-508
No abstract available....
