Deep-sea spherules from Pacific clay: Mass distribution and influx rate
M.T. Murrell, P.A. Davis Jr., K. Nishiizumi, Hugh T. Millard Jr.
1980, Geochimica et Cosmochimica Acta (44) 2067-2074
From 411 kg of Pacific clay, 22 mg of stony spherules and 50 mg of iron spherules larger than 150 μm were concentrated. The extraterrestrial origin of these particles was evaluated with the aid of both optical and electron microscopy as well as atomic absorption elemental analysis. The integral number...
Tectonic state: its significance and characterization in the assessment of seismic effects associated with reservoir impounding
R. O. Castle, M. M. Clark, A. Grantz, J.C. Savage
1980, Engineering Geology (15) 53-99
Any analysis of seismicity associated with the filling of large reservoirs requires an evaluation of the natural tectonic state in order to determine whether impoundment is the basic source, a mechanically unrelated companion feature, or a triggering stimulus of the observed seismicity. Several arguments indicate that the associated seismicity is...
Growth rates of manganese nodules in Oneida Lake, New York
W.S. Moore, W.E. Dean, S. Krishnaswami, D.V. Borole
1980, Earth and Planetary Science Letters (46) 191-200
226Ra is used to document the growth histories of six manganese nodules from Oneida Lake, New York. Detailed sectioning and analysis reveal that there are discontinuous gradients in226Ra content in these samples. These gradients result from periods of rapid growth (>1...
Results and assessment of uranium series dating of vertebrate fossils from Quaternary alluvium in Colorado
Barney J. Szabo
1980, Arctic and Alpine Research (11) 95-100
An average uranium-series age of 102,000 ± 14,000 yr for bones from Louviers Alluvium, near Denver, Colorado, is compatible with the inferred geologic age of from 120,000 to 150,000 yr. A uranium-series date of about 190,000 yr for a bone from Slocum Alluvium, near Canon City, Colorado, is consistent with...
Geodetic measurement of horizontal deformation across the Rio Grande rift near Socorro, New Mexico
J.C. Savage, M. Lisowski, W.H. Prescott, A.R. Sanford
1980, Journal of Geophysical Research Solid Earth (85) 7215-7220
Trilateration surveys of a geodetic network across the Rio Grande rift near Socorro, New Mexico, in 1972, 1973, 1976, and 1979 have failed to detect any significant strain accumulation. The surveys place an upper bound (95% confidence limit) of 1 mm/a (a = years) on east-west spreading cross the rift...
High-sensitivity aeromagnetic survey of the U.S. Atlantic continental margin
John C. Behrendt, Kim D. Klitgord
1980, Geophysics (45) 1813-1846
The U.S. Geological Survey contracted a high-sensitivity, digital aeromagnetic survey that was flown over the U.S. Atlantic continental margin over a period of 15 months between 1974 and 1976. The 185,000 km of profile data have a relative accuracy approaching a few tenths of a nanotesla, which allowed compilation into...
Clarification of the Hashin-Shtrikman bounds on the effective elastic moduli of polycrystals with hexagonal, trigonal, and tetragonal symmetries
J.P. Watt, L. Peselnick
1980, Journal of Applied Physics (51) 1525-1531
Bounds on the effective elastic moduli of randomly oriented aggregates of hexagonal, trigonal, and tetragonal crystals are derived using the variational principles of Hashin and Shtrikman. The bounds are considerably narrower than the widely used Voigt and Reuss bounds. The Voigt-Reuss-Hill average lies within the Hashin-Shtrikman bounds in nearly all...
Radiometric dating of sediments using fission tracks in conodonts
H.M. Sachs, M. Denkinger, C.L. Bennett, A. G. Harris
1980, Nature (288) 359-361
Conodonts are microfossils which are commonly found in marine rocks of Cambrian to Triassic age. Although their biological affinities are difficult to assess, conodonts are valuable stratigraphical indices for much of their geological range1. Recent work has also established that conodont colour alteration indices (CAI) are useful guides to diagenetic...
Geologic history of Grecian Rocks, Key Largo Coral Reef Marine Sanctuary.
E.A. Shinn
1980, Bulletin of Marine Science (30) 646-656
Two transects were drilled across the major ecologic zones of the c. 750 by 200 m reef, whose accumulation was controlled by a local Pleistocene topographic feature. The Reef is composed of 5 major ecologic zones: 1) a deep seaward rubble zone, 6-8 m depth; 2) a poorly developed spur...
Thickness change involved in the peat-to- coal transformation for a bituminous coal of Cretaceous age in central Utah
Thomas A. Ryer, A.W. Langer
1980, Journal of Sedimentary Petrology (50) 987-992
The ratio of the thicknesses of a layer of peat and the coal bed formed from that peat has been calculated for a bituminous coal bed in central Utah. The method used involves comparison of the thickness of peat eroded by a laterally...
Nd-isotopes in selected mantle-derived rocks and minerals and their implications for mantle evolution
A. R. Basu, M. Tatsumoto
1980, Contributions to Mineralogy and Petrology (75) 43-54
The Sm-Nd systematics in a variety of mantle-derived samples including kimberlites, alnoite, carbonatite, pyroxene and amphibole inclusions in alkali basalts and xenolithic eclogites, granulites and a pyroxene megacryst in kimberlites are reported. The additional data on kimberlites strengthen our earlier conclusion that kimberlites are derived from a relatively undifferentiated chondritic...
Depositional environments of some Pleistocene coastal terrace deposits, southwestern Oregon - case history of progradational beach and dune sequence.
R. E. Hunter
1980, Sedimentary Geology (27) 241-262
These deposits comprise a basal gravelly unit and 3 overlying sandy units, each with mud beds, a paleosol, or the modern soil in its uppermost part. The gravelly unit is interpreted as a progradational deposit. The main parts of the sandy units are made up of 1) a crossbedded sand...
Sedimentary and structural patterns on the northern Santa Rosa-Cortes Ridge, southern California
Michael E. Field, William C. Richmond
1980, Marine Geology (34) 79-98
The Santa Rosa-Cortes Ridge is an 1800 m high, 180 km long feature lying approximately 90 km off the coast of southern California and directly south of the northern group of Channel Islands. Geophysical profiling and sampling cruises to the northern part of the ridge, an area of recent and...
Opaque minerals as aids in distinguishing between source and sorting effects on beach sand mineralogy in southwestern Oregon
G. Luepke
1980, Journal of Sedimentary Petrology (50) 489-496
Both source area and wave sorting affect the heavy-mineral distributions of beach sands. Although source and sorting effects are difficult to distinguish, they can be separated on four Oregon beaches by studying the magnetic fraction of the sand. Prominent headlands bound the four...
Calculation of uncertainties of U-Pb isotope data
K.R. Ludwig
1980, Earth and Planetary Science Letters (46) 212-220
Equations are derived for the estimation of errors and error correlations for various types of U-Pb isotope data, taking into account ion-beam instabilities, run-to-run variability in mass-discrimination, uncertainties in Pb and U concentrations, and uncertainties in initial-Pb and blank-Pb amount and isotopic composition. Equations are also given for the calculation...
Distribution of Quaternary rhyolite domes of the Coso Range, California: implications for extent of the geothermal anomaly.
C. R. Bacon, W. A. Duffield
1980, Journal of Geophysical Research (85) 2425-2433
38 separate domes and flows of phenocryst-poor, high-silica rhyolite of similar major element chemical composition were erupted over the past 1My from vents arranged in a crudely S-shaped array atop a granitic horst in the Coso Range, California. Most of the extrusions are probably less than about 0.3My old. The...
Geothermal system at 21°N, East Pacific Rise: physical limits on geothermal fluid and role of adiabatic expansion
J. L. Bischoff
1980, Science (207) 1465-1469
Pressure-volume-temperature relations for water at the depth of the magma chamber at 21°N on the East Pacific Rise suggest that the maximum subsurface temperature of the geothermal fluid is about 420°C. Both the chemistry of the discharging fluid and thermal balance considerations indicate that the effective water/rock ratios in the...
Heat flow and energetics of the San Andreas fault zone
A.H. Lachenbruch, J.H. Sass
1980, Journal of Geophysical Research Solid Earth (85) 6185-6223
Approximately 100 heat flow measurements in the San Andreas fault zone indicate (1) there is no evidence for local factional heating of the main fault trace at any latitude over a 1000-km length from Cape Mendocino to San Bernardino, (2) average heat flow is high (∼2 HFU, ∼80 mW m−2)...
Littoral transport in the surf zone elucidated by an Eulerian sediment tracer
D.B. Duane, W.R. James
1980, Journal of Sedimentary Petrology (50) 929-942
An Eulerian, or time integration, sand tracer experiment was designed and carried out in the surf zone near Pt. Mugu, California on April 19, 1972. Data indicate that conditions of stationarity and finite boundaries required for proper application of Eulerian tracer theory exist...
Implications of regional gravity for state of stress in the earth's crust and upper mantle
M. McNutt
1980, Journal of Geophysical Research Solid Earth (85) 6377-6396
Topography is maintained by stress differences within the earth. Depending on the distribution of the stress we classify the support as either local or regional compensation. In general, the stresses implied in a regional compensation scheme are an order of magnitude larger than those corresponding to local isostasy. Gravity anomalies,...
Organic content of Devonian shale in western Appalachian basin
James W. Schmoker
1980, American Association of Petroleum Geologists Bulletin (64) 2156-2165
In the organic-rich facies of the Devonian shale in the western part of the Appalachian basin, the distribution of organic matter provides an indirect measure of both gas in place and the capacity of the shale to supply gas to permeable pathways.The boundary between organic-rich ('black') and organic-poor ('gray') facies...
Applications of statistics to thematic mapping.
G.H. Rosenfield, M.L. Melley
1980, Photogrammetric Engineering and Remote Sensing (46) 1287-1294
Two statistical problems occurring in the effort to analyze thematic maps and mapping are determining the accuracy of thematic content and comparing factors studied in thematic mapping. Statistical procedures applicable to thematic mapping involve sampling, determining accuracy, and comparing factors. A sampling procedure using an unaligned pattern within a square...
The provenance of rutile.
E. R. Force
1980, Journal of Sedimentary Petrology (50) 485-488
Most coarse detrital rutile is derived from high-grade metamorphic rocks. Contrary to a conventional assumption, independent rutile grains are particularly rare in igneous rocks except alkalic rocks. The use of rutile in the ZTR (zircon-tourmaline-rutile) index of mineralogic maturity is only partially valid,...
Hydrocarbon gas in sediment from the shelf, slope and basin of the Bering Sea.
K.A. Kvenvolden, G.D. Redden
1980, Geochimica et Cosmochimica Acta (44) 1145-1150
Methane, ethane, ethene, propane, propene, isobutane and n-butane are present in low concentrations in the top 2m of sediment. Methane is most abundant and its concentration increases with depth in the sediment. Ethane, ethene, propane and propene are present in almost all samples, but the concentrations of these gases are...
Speculations on processes responsible for mesoscale current lineations on the continental shelf, southern California
Herman A. Karl
1980, Marine Geology (34) M9-M18
A side-scan sonar survey of San Pedro shelf, California, reveals areas of mesoscale current lineations oriented approximately north-northeast in water depths of 20-25 m. Widths of sand ribbons range from 40 to 120 m and intervening erosional furrows, from 15 to 50 m. A conceptual model shows that the scale...
