Pleistocene high-silica rhyolites of the Coso volcanic field, Inyo County, California
C. R. Bacon, R. Macdonald, R. L. Smith, P. A. Baedecker
1981, Journal of Geophysical Research (86) 10223-10241
The high-silica rhyolite domes and lava flows of the bimodal Pleistocene part of the Coso volcanic field provide an example of the early stages of evolution of a silicic magmatic system of substantial size and longevity. Major and trace element compositions are consistent with derivation from somewhat less silicic parental...
Determination of tetraalkyllead compounds in gasoline by liquid chromatography-atomic absorption spectrometry
J. D. Messman, T. C. Rains
1981, Analytical Chemistry (53) 1632-1636
A liquid chromatography-atomic absorption spectrometry (LC-AAS) hybrid analytical technique is presented for metal speciation measurements on complex liquid samples. The versatility and inherent metal selectivity of the technique are Illustrated by the rapid determination of five tetraalkyllead compounds in commercial gasoline. Separation of the individual tetraalkyllead species is achieved by...
Estimating bird damage from damage incidence in wine grape vineyards
R. W. DeHaven, R. L. Hothem
1981, American Journal of Enology and Viticulture (32) 1-4
Bird damage was measured during 1977 and 1978 at 32 wine grape vineyards in the San Joaquin Valley and North Coastal Region of California. Both the percentage bird loss (PBL) and the percentage of bunches damaged (BDI = bird damage incidence) were determined during 55 total-damage assessments, and the resulting...
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...
Paleogeography and sedimentology of Upper Cretaceous turbidites, San Diego, California
T. H. Nilsen, P. L. Abbott
1981, American Association of Petroleum Geologists Bulletin (65) 1256-1284
Upper Cretaceous (Campanian and Maestrichtian) marine strata of the Rosario Group in the San Diego area include the Point Loma Formation and overlying Cabrillo Formation. These units contain six facies associations: (1) shelf and lagoonal sandstone, (2) slope and basin-plain(?) mudstone, (3) outer-fan lobe sandstone, (4) middle-fan channel-fill sandstone, (5)...
Variations in stable- isotope ratios of ground waters in seismically active regions of California
J. R. O’Neil, Chi-Yu King
1981, Geophysical Research Letters (8) 429-432
Measurements of D and 18O concentrations of ground waters in seismically active regions are potentially useful in earthquake prediction and in elucidating mechanisms operative during earthquakes. Principles of this method are discussed and some preliminary data regarding a magnitude 5.7 earthquake at the Oroville Dam in 1975...
Reduction of matrix interferences in furnace atomic absorption with the L'vov Platform
M. L. Kaiser, S. R. Koirtyohann, E. J. Hinderberger, Howard E. Taylor
1981, Spectrochimica Acta Part B: Atomic Spectroscopy (36) 773-783
Use of a modified L'vov Platform and ammonium phosphate as a matrix modifier greatly reduced matrix interferences in a commercial Massmann-type atomic absorption furnace. Platforms were readily fabricated from furnace tubes and, once positioned in the furnace, caused no inconvenience in operation. Two volatile elements (Pb, Cd), two of intermediate...
Rates and possible causes of neotectonic vertical crustal movements of the emerged southeastern United States Atlantic coastal plain
T. M. Cronin
1981, Geological Society of America Bulletin (92) 812-833
Emerged Pliocene and Pleistocene shorelines and associated marine deposits were used to determine the magnitude and rate of vertical crustal movement during the past 3 m.y. in the United States Atlantic Coastal Plain of South and North Carolina. On the basis of a...
Estimation of accumulation parameters for urban runoff quality modeling
William M. Alley, Peter E. Smith
1981, Water Resources Research (17) 1657-1664
Many recently developed watershed models utilize accumulation and washoff equations to simulate the quality of runofffrom urban impervious areas. These models often have been calibrated by trial and error and with little understanding of model sensitivity to the various parameters. Methodologies for estimating best fit values of the washoff parameters...
Laser fluorometric analysis of plants for uranium exploration
T. F. Harms, F. N. Ward, J. A. Erdman
1981, Journal of Geochemical Exploration (15) 617-623
A preliminary test of biogeochemical exploration for locating uranium occurrences in the Marfa Basin, Texas, was conducted in 1978. Only 6 of 74 plant samples (mostly catclaw mimosa, Mimosa biuncifera) contained uranium in amounts above the detection limit (0.4 ppm in the ash) of the conventional fluorometric method. The samples were...
The P-wave velocity of the uppermost mantle of the Rio Grande rift region of north central New Mexico
J.N. Murdock, L.H. Jaksha
1981, Journal of Geophysical Research Solid Earth (86) 7055-7063
A network of seismograph stations has operated in north-central New Mexico since 1975. The network is approximately 200 by 300 km in size and encompasses the Rio Grande rift there. Several seismic refraction experiments have been reported in the literature for the region of the network and adjacent areas. Because...
Geology of central Lake Michigan
R. J. Wood, R. A. Paull, C. A. Wolosin, R. J. Friedel
1981, American Association of Petroleum Geologists Bulletin (65) 1621-1632
The geology beneath Lake Michigan between 43°00' and 44°00' N and between 86°30' and 87°40' W is interpreted from a synthesis of 1,700 km of continuous seismic reflection profile data, bathymetry, grab samples, and onshore surface and subsurface information.The continuous seismic reflection profiles and bathymetry provided information for maps of...
U-Pb isotope systematics and age of uranium mineralization, Midnite mine, Washington.
K.R. Ludwig, J. T. Nash, C. W. Naeser
1981, Economic Geology (76) 89-110
Uranium ores at the Midnite mine, near Spokane, Washington, occur in phyllites and calcsilicates of the Proterozoic Togo Formation, near the margins of an anomalously uraniferous, porphyritic quartz monzonite of Late Cretaceous age. The present geometry of the ore zones is tabular, with the thickest zones above depressions in the...
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...
Radial outflow and unsteady retreat of late Wisconsin to early Holocene icecap in the northern Long Range upland, Newfoundland
R. B. Waitt Jr.
1981, Geological Society of America Bulletin (92) 834-838
A swampy very low-relief drift terrain along the medial zone of the northern Long Range Mountains passes outward into fresh glacially eroded bed rock of low to moderate relief. Striations, crescentic gouges, lunate fractures, streamlined stoss-and-ice surfaces, erratics, and other evidence in the...
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....
The earliest seeds
W.H. Gillespie, G.W. Rothwell, S.E. Scheckler
1981, Nature (293) 462-464
Lagenostomalean-type seeds in bifurcating cupule systems have been discovered in the late Devonian Hampshire Formation of Randolph County, West Virginia, USA (Fig. 1). The associated megaflora, plants from coal balls, and vertebrate and invertebrate faunas demonstrate that the material is Famennian; the microflora indicates a more specific Fa2c age. Consequently,...
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...
Sr isotopic tracer study of the Samail ophiolite, Oman
M. A. Lanphere, R. G. Coleman, C.A. Hopson
1981, Journal of Geophysical Research Solid Earth (86) 2709-2720
We have measured Rb and Sr concentrations and Sr isotopic compositions in 41 whole-rock samples and 12 mineral separates from units of the Samail ophiolite, including peridotite, gabbro, plagiogranite, diabase dikes, and gabbro and websterite dikes within the metamorphic peridotite. Ten samples of cumulate gabbro from the Wadir Kadir section...
Location of the Border Ranges fault southwest of Kodiak Island, Alaska
M. A. Fisher
1981, Geological Society of America Bulletin (92) 19-30
A positive magnetic anomaly extends discontinuously from the south side of the Copper River basin, along the southeast side of Cook Inlet and Shelikof Strait, and southwestward from Kodiak Island to near Sutwik Island. Regionally, this anomaly parallels the Border Ranges fault and...
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;...
Comparison of automated segmented-flow and discrete analyzers for the determination of nutrients in water
V.C. Marti, D.R. Hale
1981, Environmental Science & Technology (15) 711-713
Water samples with specific conductances ranging from 66 to 6950 ??mho/cm at 25 ??C were analyzed for ammonia-N (NH3-N), nitrate plus nitrite-N (NO3 + NO2-N), nitrite-N (NO2-N), and phosphate-P (PO4-P) by using both a "segmented-flow" analyzer and a "discrete" analyzer. Plots of the discrete vs. the segmented-flow results showed linear...
The Lasky cumulative tonnage-grade relationship; a reexamination
J. H. DeYoung
1981, Economic Geology (76) 1067-1080
The need for interdisciplinary research on resource appraisal techniques was recognized by Samuel G. Lasky, a U.S. Geological Survey geologist, more than 30 years ago. His efforts to devise an appraisal technique that incorporated many attributes of mineral resources resulted in a cumulative tonnage-grade relationship that has been referred to...
U-Th-Pb systematics of some granitoids from the northeastern Yilgarn Block, Western Australia and implications for uranium source rock potential
J. S. Stuckless, J.A. Bunting, Ignatius T. Nkomo
1981, Journal of the Geological Society of Australia (28) 365-375
The Mount Boreas‐type granite and spatially associated syenitic granitoid of Western Australia yield Pb‐Pb ages of 2370 ± 100 Ma and 2760 ± 210 Ma, respectively. Th‐Pb ages, although less precise, are concordant with these ages, and therefore the apparent ages are interpreted to be the crystallisation ages for these two units....
Earthquakes, September-October 1980
W. J. Person
1981, Earthquake Information Bulletin (USGS) (13) 105-106
There were two major (magnitudes 7.0-7.9) earthquakes during this reporting period; a magnitude (M) 7.3 in Algeria where many people were killed or injured and extensive damage occurred, and an M=7.2 in the Loyalty Islands region of the South Pacific. Japan was struck by a damaging earthquake on September 24,...
