Monitoring of secular gravity change in southern California     

William E. Strange 《Tectonophysics》1979,52(1-4)

Repeat gravity measurements have been carried out over more than 1000 km of level lines in southern California. The initial surveys over a number of these lines were made in 1962. Repeat gravity survey lines are located primarily in the San Joaquin Valley, in the Los Angeles and Palmdale areas and in the Imperial Valley. Secular changes of gravity have been noted in a number of areas. In areas of subsidence, due to groundwater withdrawal, direct correlation between elevation and gravity change is found. In areas of vertical crustal motion along fault zones, such as in the Palmdale area, gravity changes are also noted. However, these are not, in general, directly related to elevation change. Apparently, subsurface mass redistributions are associated with the vertical motions noted in fault-zone areas before and after earthquakes. Several possible models to explain the gravity observations are being explored.  相似文献   

Aging and strain softening model for episodic faulting     

William D. Stuart 《Tectonophysics》1979,52(1-4)

Episodic slip on shallow crustal faults can be qualitatively explained by postulating a fault constitutive law that is the superposition of two limiting material responses: (1) strain softening after peak stress during large strain rates, and (2) strength (peak stress) recovery during aging at small strain rates. A single law permits a variety of seismic and aseismic phenomena to occur over a range of space and time scales. Specific cases are determined by the spatial variation of material constants, recent deformation history, crustal rigidity, and remote forcing.  相似文献   

Removal of contaminants from landfill leachates by filtration through glauconitic greensands     

Nenad Spoljaric  William A. Crawford 《Environmental Geology》1978,2(6):359-363

Passing landfill leachate through glauconitic greensand filters reduces the heavy metal cation content, lessens the unpleasant odor, and diminishes the murkiness of the leachate. The capability of the greensand to trap metal cations is increased by prolonging the contact time between the leachate and the greensand. Flushing the charged greensand filter with water does not cause significant release of cations back into solution, suggesting that polluted greensand might be disposed of at landfill sites without endangering the quality of either ground or surface water.  相似文献   

Glauconitic greensand: A possible filter of heavy metal cations from polluted waters     

Nenad Spoljaric  William A. Crawford 《Environmental Geology》1978,2(4):215-221

Experiments using distilled water, spiked with heavy metal cations and passed through a filtration system composed of greensand containing 80% glauconite at a rate of 2–4 ml/min, showed: (1) starting fluids containing Cd, Co, Cu, Pb, Mn, Ni, Ag, or Zn had an average of 90% of the contaminating cation removed from acidic solutions and an average of 84% removed from the basic solutions; and, (2) filtration through greensand tended to neutralize both acidic and basic solutions. The removal of the contaminant cation from starting fluids containing K, Na, Ca, Mg, Fe, Si, or Al (the principal constituents of glauconite plus Ca from shell material) is not as consistently effective as for the first named metals.  相似文献   

Global changes in postglacial sea level: A numerical calculation   总被引：2，自引：0，他引：2  

James A. Clark  William E. Farrell  W. Richard Peltier 《Quaternary Research》1978,9(3):265-287

The sea-level rise due to ice-sheet melting since the last glacial maximum was not uniform everywhere because of the deformation of the Earth's surface and its geoid by changing ice and water loads. A numerical model is employed to calculate global changes in relative sea level on a spherical viscoelastic Earth as northern hemisphere ice sheets melt and fill the ocean basins with meltwater. Predictions for the past 16,000 years explain a large proportion of the global variance in the sea-level record, particularly during the Holocene. Results indicate that the oceans can be divided into six zones, each of which is characterized by a specific form of the relative sea-level curve. In four of these zones emerged beaches are predicted, and these may form even at considerable distance from the ice sheets themselves. In the remaining zones submergence is dominant, and no emerged beaches are expected. The close agreement of these predictions with the data suggests that, contrary to the beliefs of many, no net change in ocean volume has occurred during the past 5000 years. Predictions for localities close to the ice sheets are the most in error, suggesting that slight modifications of the assumed melting history and/or the rheological model of the Earth's interior are necessary.  相似文献   

Vibrational structure of the S 2 − luminescence in scapolite     

R. P. Burgner  Barry E. Scheetz  William B. White 《Physics and Chemistry of Minerals》1978,2(4):317-324

An analysis has been made of the strong yellow luminescence of S ₂ ^? in the silicate mineral scapolite. The emission spectrum is dependent upon excitation wavelength, indicating that S ₂ ^? occupies several different sites. The vibrational constants for the ground state average 609 cm^?1 for ω″₀, while ω″₀χ″₀=2.2cm^?1. For the excited state ω′₀=399cm^?1 and ω′₀χ′₀=1.0cm^?1. The intensities of the vibrational bands are described by a simple harmonic oscillator calculation.  相似文献   

Movements and population structure of Atlantic menhaden indicated by tag returns     

William R. Nicholson 《Estuaries and Coasts》1978,1(3):141-150

Over 968,000 adult Atlantic menhaden,Brevoortia tyrannus, were tagged from 1967 to 1969 and over 85,000 juvenile menhaden were tagged from 1969 to 1973. Recoveries of these tagged fish through 1975 provide direct evidence that Atlantic menhaden consist of a single population that over-winters in offshore waters off the southeastern coast of the United States, moves northward in spring and stratifies along the coast by age and size during summer, and moves southward in late autumn.  相似文献   

Partitioning of Ni²⁺ between basaltic and synthetic melts and olivines—an experimental study     

William P. Leeman  David J. Lindstrom 《Geochimica et cosmochimica acta》1978,42(6):801-816

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Interstitial water chemistry in the sediments of Saanich Inlet     

James W. Murray  Varis Grundmanis  William M. Smethie 《Geochimica et cosmochimica acta》1978,42(7):1011-1026

Measurements of nutrients and trace metals are used to examine the processes controlling their distributions in the interstitial waters of Saanich Inlet. Samples were collected using both in situ and squeezing techniques with excellent agreement. Additional measurements of porosity, organic carbon and sedimentation rate by ²¹⁰Pb are used in conjunction with the nutrient measurements to test the equation for the diagenesis of organic matter in fine-grained, organic-rich and rapidly-accumulating sediments.Organic carbon and sulfate decrease with depth in the sediment whereas ammonia and alkalinity increase. In the zone of sulfate reduction (0–20 cm) the rate constants for sulfate reduction ($\text{k}{}_{\mathrm{s}}$), ammonia production ($\text{k}{}_{\mathrm{N}}$) and organic carbon decomposition ($\text{k}{}_{\mathrm{c}}$) agree within a factor of two. Our calculations indicate, however, that this is fortuitous since the observed decrease in paniculate organic carbon is insufficient to account for the sulfate consumption. Sulfate must also be consumed by reaction with methane diffusing up from the underlying sediments. The rate constant for sulfate reduction using particulate organic carbon is lower than a modelled rate encompassing all organic species, including methane.The rate constant for ammonia production ($\text{k}{}_{\mathrm{N}}$) decreases by an order of magnitude when sulfate is completely depleted and methane production dominates.Thermodynamic calculations suggest that the interstitial waters are saturated or supersaturated with respect to all forms of iron ‘monosulfides’, apatite and rhodochrosite.  相似文献   

Reply to comments by P. F. Karrow and R. F. Black     

Edward B. Evenson  William R. Farrand  Donald F. Eschman  David M. Mickelson  Louis J. Maher 《Quaternary Research》1978,9(1):123-129

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