An interpretation of episodic slip on the Calaveras fault near Hollister, California
J. O. Langbein
1981, Journal of Geophysical Research Solid Earth (86) 4941-4948
Data from a precision multi-wavelength distance measuring (MWDM) instrument, located near Hollister, California, have been analyzed in terms of strike-slip faulting in the region covered by the network. Four episodes of deformation that are readily identifiable in the MWDM data for the year following September 1975 can be modeled as...
Chemical constraints of groundwater management in the Yucatan peninsula, Mexico
W. Back, J.M. Lesser
1981, Journal of Hydrology (51) 119-130
Two critical objectives of water management in the Yucatan are: (1) to develop regional groundwater supplies for an expanding population and tourism based on the Mayan archeological sites and excellent beaches; and (2) to control groundwater pollution in a chemically sensitive system made...
Multiple-element semiquantitative analysis of one-milligram geochemical samples by D.C. arc emission spectrography
N. Rait
1981, Chemical Geology (32) 317-333
A modified method is described for a 1-mg sample multi-element semiquantitative spectrographic analysis. This method uses a direct-current arc source, carbon instead of graphite electrodes, and an 80% argon-20% oxygen atmosphere instead of air. Although this is a destructive method, an analysis can be made for 68 elements in all...
Correlation of natural gas content to iron species in the New Albany shale group
R.H. Shiley, R.M. Cluff, D. R. Dickerson, C.C. Hinckley, Gerard V. Smith, H. Twardowska, Mykola Saporoschenko
1981, Fuel (60) 732-738
Mössbauer parameters were obtained for four Illinois Basin shales and their corresponding < 2μm clay fractions from wells drilled through the New Albany Shale Group in Henderson, Tazewell, and Effingham counties in Illinois and Christian County in Kentucky. Off-gas analysis indicated that the Illinois cores were in an area of...
A stochastic fault model. 2. Time-dependent case
D.J. Andrews
1981, Journal of Geophysical Research Solid Earth (86) 10821-10834
A random model of fault motion in an earthquake is formulated by assuming that the slip velocity is a random function of position and time truncated at zero, so that it does not have negative values. This random function is chosen to be self-affine; that is, on change of length...
Seawater sulfate reduction and sulfur isotope fractionation in basaltic systems: interaction of seawater with fayalite and magnetite at 200–350°C
Wayne C. Shanks III, James L. Bischoff, Robert J. Rosenbauer
1981, Geochimica et Cosmochimica Acta (45) 1977-1995
Sulfate reduction during seawater reaction with fayalite and with magnetite was rapid at 350°C, producing equilibrium assemblages of talc-pyrite-hematite-magnetite at low water/rock ratios and talc-pyrite-hematite-anhydrite at higher water/rock ratios. At 250°C, seawater reacting with fayalite produced detectable amounts of dissolved H2S, but extent of reaction of solid phases was...
Aeromagnetic and radio echo ice-sounding measurements over the Dufek intrusion, Antarctica
John C. Behrendt, D.J. Drewry, E. Jankowski, M. S. Grim
1981, Journal of Geophysical Research Solid Earth (86) 3014-3020
A combined aeromagnetic and radio echo ice-sounding survey (4200 km of traverse) made in 1978 in Antarctica over the Dufek layered mafic intrusion of Jurassic age suggests a minimum area of about 50,000 km2, making it comparable in size with the Bushveld Complex of Africa. Comparisons of the magnetic and...
Interpretation of changes in water level accompanying fault creep and implications for earthquake prediction
R. L. Wesson
1981, Journal of Geophysical Research Solid Earth (86) 9259-9267
Quantitative calculations for the effect of a fault creep event on observations of changes in water level in wells provide an approach to the tectonic interpretation of these phenomena. For the pore pressure field associated with an idealized creep event having an exponential displacement versus time curve, an analytic expression...
A transient laboratory method for determining the hydraulic properties of 'tight' rocks-I. Theory
P. A. Hsieh, J.V. Tracy, C. E. Neuzil, J.D. Bredehoeft, Stephen E. Silliman
1981, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts (18) 245-252
Transient pulse testing has been employed increasingly in the laboratory to measure the hydraulic properties of rock samples with low permeability. Several investigators have proposed a mathematical model in terms of an initial-boundary value problem to describe fluid flow in a transient pulse test. However, the solution of this problem...
Ne matrix spectra of the sym-C6Br3F3+ radical cation
V.E. Bondybey, T.J. Sears, T.A. Miller, C. Vaughn, J.H. English, R.S. Shiley
1981, Chemical Physics (61) 9-16
The electronic absorption and laser excited, wavelength resolved fluorescence spectra of the title cation have been observed in solid Ne matrix and vibrationally analysed. The vibrational structure of the excited B2A2??? state shows close similarity to the parent compound. The X2E??? ground state structure is strongly perturbed and irregular owing...
Determination of sub-microgram amounts of selenium in geological materials by atomic-absorption spectrophotometry with electrothermal atomisation after solvent extraction
R. F. Sanzolone, T. T. Chao
1981, The Analyst (106) 647-652
An atomic-absorption spectrophotometric method with electrothermal atomisation has been developed for the determination of selenium in geological materials. The sample is decomposed with a mixture of nitric, perchloric and hydrofluoric acids and heated with hydrochloric acid to reduce selenium to selenium(IV). Selenium is then extracted into toluene from a hydrochloric...
Multiple asperity model for earthquake prediction
M. Wyss, A. C. Johnston, F. W. Klein
1981, Nature (289) 231-234
Large earthquakes often occur as multiple ruptures reflecting strong variations of stress level along faults. Dense instrument networks with which the volcano Kilauea is monitored provided detailed data on changes of seismic velocity, strain accumulation and earthquake occurrence rate before the 1975 Hawaii 7.2-mag earthquake. During the ???4 yr of...
Chemical modifications accompanying blueschist facies metamorphism of Franciscan conglomerates, Diablo Range, California
Diane E. Moore, J. G. Liou, B.-S. King
1981, Chemical Geology (33) 237-263
As part of an investigation of blueschist-facies mineral parageneses in pebbles and matrix of some Franciscan metaconglomerates of the Diablo Range, California, textural and major-element chemical analyses were conducted on a number of igneous pebbles that comprise a range of rock types from granite and dacite to gabbro and basalt....
Flow through fractures
C. E. Neuzil, James V. Tracy
1981, Water Resources Research (17) 191-199
Flow through fractures is often idealized as flow between two parallel plates (plane Poiseuille flow). The opening or aperture between parallel plates is unambiguous and its relation to flowrate is well known. However, fractures in rock have uneven walls and a variable aperture. A model for flow in a fracture...
Concentration of some platinum-group metals in coal
R. B. Finkelman, P. J. Aruscavage
1981, International Journal of Coal Geology (1) 95-99
New data on some platinum group metals in coal indicate that the concentration of Pt is generally less than about 5 ppb, that of Pd is generally less than 1 ppb, and that of Rh is generally less than 0.5 ppb....
Economics and coal resource appraisal: strippable coal in the Illinois Basin ( USA)
E. D. Attanasi, E.K. Green
1981, Southern Economic Journal (47) 742-752
Coal-resource appraisals generally describe the location and general characteristics of coal beds. Estimates are made of the average overburden depth (depth of the coal bed below the surface), bed thickness, and perhaps certain chemical properties of the coal [1]. Although such resource compilations represent an important initial step, neither they...
Earthquakes, March-April 1981
W. J. Person
1981, Earthquake Information Bulletin (USGS) (13) 195-198
There was on major earthquake (7.0-7.9) during this reporting period on April 24 in the Vanuatu Islands (formerly the New Hebrides islands). the series of strong earthquakes continued in Greece and caused additional casualties and damage, and Peru expereinced a moderate earthquake that caused fatalities and damage on April 18. In...
Sm-Nd systematics of a tonalitic augen gneiss and its constituent minerals from northern Michigan
K. Futa
1981, Geochimica et Cosmochimica Acta (45) 1245-1249
The Sm-Nd isotopic system of a tonalitic augen gneiss and its constituent minerals from northern Michigan was disturbed during metamorphism. Sm-Nd zircon ages are lower than the wholerock Sm-Nd model age. However, closely associated pairs of minerals (for example, sphene and biotite or apatite and plagioclase) retain their apparent metamorphic...
Significant results from using earth observation satellites for mineral and energy resource exploration
William D. Carter
1981, Advances in Space Research (1) 261-269
A large number of Earth-observation satellites orbit our world several times each day, providing new information about the land and sea surfaces and the overlying thin layer of atmosphere that makes our planet unique. Meteorological satellites have had the longest history of experimental use and most are now considered operational....
Role of solute-transport models in the analysis of groundwater salinity problems in agricultural areas
Leonard F. Konikow
1981, Agricultural Water Management (4) 187-205
Undesirable salinity increases occur in both groundwater and surface water and are commonly related to agricultural practices. Groundwater recharge from precipitation or irrigation will transport and disperse residual salts concentrated by evapotranspiration, salts leached from soil and aquifer materials, as well as some dissolved fertilizers and pesticides. Where stream salinity...
Stable isotope systematics in mesozoic granites of Central and Northern California and Southwestern Oregon
U. Masi, J. R. O’Neil, R. W. Kistler
1981, Contributions to Mineralogy and Petrology (76) 116-126
18O, D, and H2O+ contents were measured for whole-rock specimens of granitoid rocks from 131 localitics in California and southwestern Oregon. With 41 new determinations in the Klamath Mountains and Sierra Nevada, initial strontium isotope ratios are known for 104 of these samples. Large variations in ??18O (5.5 to 12.4),...
Sedimentary framework of the Potomac River estuary, Maryland
Harley J. Knebel, E. Ann Martin, J.L. Glenn, Sally W. Needell
1981, Geological Society of America Bulletin (92) 578-589
Analyses of seismic-reflection profiles, sediment cores, grab samples, and side-scan sonar records, along with previously collected borehole data, reveal the characteristics, distribution, and geologic history of the shallow strata beneath the Potomac River estuary. The lowermost strata are sediments of the Chesapeake Group (lower Miocene to lower Pleistocene) that crop...
A review of regional mineral resource assessment methods
D.A. Singer, D.L. Mosier
1981, Economic Geology (76) 1006-1015
Over 100 papers on regional mineral resource assessment of nonfuels are classified according to method(s) used and form(s) of product in order to help identify possible methods for future assessments. Types of products that have been used include: tons of metal; tons of rock and associated grade; gross value; potential;...
Blast dynamics at Mount St Helens on 18 May 1980
S. W. Kieffer
1981, Nature (291) 568-570
At 8.32 a.m. on 18 May 1980, failure of the upper part of the north slope of Mount St Helens triggered a lateral eruption ('the blast') that devastated the conifer forests in a sector covering ???500 km2 north of the volcano. I present here a steady flow model for the...
Northwest margin of California continental borderland: Marine geology and tectonic evolution
J.K. Crouch
1981, American Association of Petroleum Geologists Bulletin (65) 191-218
The northwest margin of the California continental borderland consists mainly of two northwest-trending pre-Neogene lithologic belts blanketed by Miocene and younger strata. These belts, which are lithologically and structurally correlated with the Franciscan Complex and Great Valley sequence of northern California, are interpreted to represent facies corresponding to the subduction...
