The 1979 Homestead Valley earthquake sequence, California: Control of aftershocks and postseismic deformation
R.S. Stein, M. Lisowski
1983, Journal of Geophysical Research Solid Earth (88) 6477-6490
The coseismic slip and geometry of the March 15, 1979, Homestead Valley, California, earthquake sequence are well constrained by precise horizontal and vertical geodetic observations and by data from a dense local seismic network. These observations indicate 0.52±0.10 m of right-lateral slip and 0.17±0.04 m of reverse slip on a...
Evidence for dyke intrusion earthquake mechanisms near long valley caldera, California
B.R. Julian
1983, Nature (303) 323-325
A re-analysis of the magnitude 6 earthquakes that occurred near Long Valley caldera in eastern California on 25 and 27 May 1980, suggests that at least two of them, including the largest, were probably caused by fluid injection along nearly vertical surfaces and not by slip on faults. Several investigators...
Process and rate of dedolomitization: Mass transfer and C14 dating in a regional carbonate aquifer
W. Back, B.B. Hanshaw, Niel Plummer, P.H. Rahn, C.T. Rightmire, M. Rubin
1983, Geological Society of America Bulletin (94) 1415-1429
Regional dedolomitization is the major process that controls the chemical character of water in the Mississippian Pahasapa Limestone (Madison equivalent) surrounding the Black Hills, South Dakota and Wyoming. The process of dedolomitization consists of dolomite dissolution and concurrent precipitation of calcite; it is...
U. S. GEOLOGICAL SURVEY LAND REMOTE SENSING ACTIVITIES.
Doyle G. Frederick
1983, Conference Paper
USGS uses all types of remotely sensed data, in combination with other sources of data, to support geologic analyses, hydrologic assessments, land cover mapping, image mapping, and applications research. Survey scientists use all types of remotely sensed data with ground verifications and digital topographic and cartographic data. A considerable amount...
Hafnium isotope results from mid-ocean ridges and Kerguelen.
P. J. Patchett
1983, LITHOS (16) 47-51
176Hf/177Hf ratios are presented for oceanic volcanic rocks representing both extremes of the range of mantle Hf-Nd-Sr isotopic variation. Hf from critical mid-ocean ridge basalts shows that 176Hf/177Hf does indeed have a greater variability than 143Nd/144Nd and 87Sr/86Sr in the depleted mantle. This extra variation is essentially of a random...
Geophysical Logging in Carbonate Aquifers
L.M. MacCary
1983, Groundwater (21) 334-342
Some logging methods are inherently superior to others for the analysis of limestone and dolomite aquifers. Three such systems are the density, neutron, and acousticvelocity logs.Relative percentages of limestone and dolomite, average matrix (grain) densities of the rock mixtures, and porosity of the rock mass...
Birdseyes, fenestrae, shrinkage pores, and loferites: a reevaluation
E.A. Shinn
1983, Journal of Sedimentary Petrology (53) 619-628
Birdseyes, birdseye limestone, fenestrae, fenestral fabric, shrinkage pores, and loferites are considered similar or synonymous when occurring in lime mudstone or syndepositional dolomite, especially in association with mudcracks and stromatolites. Compaction experiments indicate, however, that without early cementation, these vugs can be obliterated,...
DIGITAL GEOLOGIC MAP OF THE UNITED STATES.
Patricia Fulton
1983, Conference Paper, Technical Papers of the American Congress of Surveying and Mapping
The geologic map of the United States was published in 1974 by the U. S. Geological Survey. This major publication contains an enormous amount of information on the surficial geology of the United States. Many geologists have used this map as a research tool. Most have needed information from only...
Automated determination of bromide in waters by ion chromatography with an amperometric detector
G. S. Pyen, D. E. Erdmann
1983, Analytica Chimica Acta (149) 355-358
An automated ion chromatograph, including a program controller, an automatic sampler, an integrator, and an amperometric detector, was used to develop a procedure for the determination of bromide in rain water and many ground waters. Approximately 10 min is required to obtain a chromatogram. The detection limit for bromide is...
Palaeomagnetism of lower cretaceous tuffs from Yukon-Kuskokwim delta region, western Alaska
B.R. Globerman, R. S. Coe, J. M. Hoare, J. Decker
1983, Nature (305) 516-520
During the past decade, the prescient arguments1-3 for the allochthoneity of large portions of southern Alaska have been corroborated by detailed geological and palaeomagnetic studies in south-central Alaska 4-9 the Alaska Peninsula10, Kodiak Island11,12 and the Prince William Sound area13 (Fig. 1). These investigations have demonstrated sizeable northward displacements for...
Remote detection of metal anomalies on Pilot Mountain, Randolph County, North Carolina
N.M. Milton, W. Collins, Sheng-Huei Chang, R. G. Schmidt
1983, Economic Geology (78) 605-617
Pilot Mountain, a hydrothermally altered monadnock within the Carolina slate belt, contains areas of anomalously high amounts of Cu, Mo, and Sn in the soils. Leaves of canopy trees in the mineralized zone also contain more copper than trees in a nearby control area. Spectral data were processed using a...
Importance of the Lu-Hf isotopic system in studies of planetary chronology and chemical evolution
P. J. Patchett
1983, Geochimica et Cosmochimica Acta (47) 81-91
The 176Lu-176Hf isotope method and its applications in earth sciences are discussed. Greater fractionation of Lu/Hf than Sm/Nd in planetary magmatic processes makes 176Hf177Hf">176Hf177Hf a powerful geochemical tracer. In general, proportional variations of 176Hf177Hf"><span...
A review of distributed parameter groundwater management modeling methods
Steven M. Gorelick
1983, Water Resources Research (19) 305-319
Models which solve the governing groundwater flow or solute transport equations in conjunction with optimization techniques, such as linear and quadratic programing, are powerful aquifer management tools. Groundwater management models fall in two general categories: hydraulics or policy evaluation and water allocation. Groundwater hydraulic management models enable the determination of...
Statistical averaging of marine magnetic anomalies and the aging of oceanic crust
R.J. Blakely
1983, Journal of Geophysical Research Solid Earth (88) 2289-2296
Visual comparison of Mesozoic and Cenozoic magnetic anomalies in the North Pacific suggests that older anomalies contain less short-wavelength information than younger anomalies in this area. To test this observation, magnetic profiles from the North Pacific are examined from crust of three ages: 0–2.1, 29.3–33.1, and 64.9–70.3 m.y, B.P. For...
Faulting arrested by control of ground-water withdrawal in Houston, Texas
T. Holzer, R.K. Gabrysch, E.R. Verbeek
1983, Earthquake Information Bulletin (USGS) (15) 204-209
More than 86 historically active faults with an aggregate length of 150 miles have been identified within and adjacent to the Houston, Texas, metropolitan area. Although scarps of these faults grow gradually and without causing damaging earthquakes, historical fault offset has cost millions of dollars in damage to houses and...
Role of fluid mixing and fault-related sulfide in the origin of the Ray Point uranium district, south Texas
M. B. Goldhaber, R. L. Reynolds, R. O. Rye
1983, Economic Geology (78) 1043-1063
The Lamprecht and Felder deposits are roll-type deposits hosted by the Miocene Oakville Sandstone. Four distinct stages of FeS 2 mineral formation are recognized: (1) a generation of isotopically light (delta 34 S < -20 per mil) preore pyrite, (2) a generation of isotopically light (delta 34 S < -20 per mil) marcasite that formed mostly...
Estimation of groundwater recharge parameters by time series analysis
Richard L. Naff, Allan L. Gutjahr
1983, Water Resources Research (19) 1531-1546
A model is proposed that relates water level fluctuations in a Dupuit aquifer to effective precipitaton at the top of the unsaturated zone. Effective precipitation, defined herein as that portion of precipitation which becomes recharge, is related to precipitation measured in a nearby gage by a two-parameter function. A second-order...
The use of MAGSAT data to determine secular variation
J.C. Cain, J. Frayser, L. Muth, D. Schmitz
1983, Journal of Geophysical Research Solid Earth (88) 5903-5910
A combined spatial and secular variation model of the geomagnetic field, labeled M061581, is derived from a selection of Magsat data. Secular variation (SV) data computed from linear fits to midnight hourly values from 19 magnetic observatories were also included in the analysis but were seen to have little effect...
Expendable bubble tiltmeter for geophysical monitoring
J.A. Westphal, M.A. Carr, W.F. Miller, D. Dzurisin
1983, Review of Scientific Instruments (54) 415-418
An unusually rugged highly sensitive and inexpensive bubble tiltmeter has been designed, tested, and built in quantity. These tiltmeters are presently used on two volcanoes and an Alaskan glacier, where they continuously monitor surface tilts of geological interest. This paper discusses the mechanical, thermal, and electric details of the meter,...
Present and former equilibrium-line altitudes near Mount Everest, Nepal and Tibet
V. S. Williams
1983, Arctic and Alpine Research (15) 201-211
New information on equilibrium-line altitudes (ELAs) of present and former glaciers in the Mount Everest area of eastern Nepal and southern Tibet has been derived from field mapping and interpretation of topographic maps and Landsat imagery. Present ELAs rise from south to north across the Himalayan Range from 5200 to...
Major and trace elements in Mahogany zone oil shale in two cores from the Green River Formation, piceance basin, Colorado
M. L. Tuttle, W.E. Dean, N. L. Parduhn
1983, Conference Paper, Preprints Symposia
The Parachute Creek Member of the lacustrine Green River Formation contains thick sequences of rich oil-shale. The richest sequence and the richest oil-shale bed occurring in the member are called the Mahogany zone and the Mahogany bed, respectively, and were deposited in ancient Lake Uinta. The name "Mahogany" is derived...
Distribution of oceanic and continental leads in the Arabian-Nubian Shield
J. S. Stacey, D. B. Stoeser
1983, Contributions to Mineralogy and Petrology (84) 91-105
New common lead data for feldspar, whole-rock, and galena samples from the Arabian-Nubian Shield, together with data from previous work, can be divided into two main groups. Group I leads have oceanic (mantle) characteristics, whereas group II leads have incorporated a continental-crustal component of at least early Proterozoic age. The...
A method of calculating quartz solubilities in aqueous sodium chloride solutions
R.O. Fournier
1983, Geochimica et Cosmochimica Acta (47) 579-586
The aqueous silica species that form when quartz dissolves in water or saline solutions are hydrated. Therefore, the amount of quartz that will dissolve at a given temperature is influenced by the prevailing activity of water. Using a standard state in which there are 1,000 g of water (55.51 moles)...
Paleohydraulic reconstruction of flash- flood peaks from boulder deposits in the Colorado Front Range
J. E. Costa
1983, Geological Society of America Bulletin (94) 986-1004
Nine watersheds in the Colorado Front Range with steep bedrock channels were used to test the accuracy of paleohydraulic reconstruction of large flash floods using boulder deposits. The nine basins consist of eight small ungauged basins ranging in size from 1.6 to 29...
Influence of the Onion Creek salt diapir on the late Cenozoic history of Fisher Valley, southeastern Utah
Steven M. Colman
1983, Geology (11) 240-243
More than 140 m of upper Cenozoic basin-fill sediments were deposited and then deformed in Fisher Valley between about 2.5 and 0.25 m.y. ago, in response to uplift of the adjacent Onion Creek salt diapir. In addition to these basin-fill sediments, minor amounts of eolian and fluvial sand were deposited...
