Chronologic and isotopic framework for early Proterozoic crustal evolution in the eastern Mojave Desert region, SE California
J. L. Wooden, D. M. Miller
1990, Journal of Geophysical Research (95) 20133-20146
The Early Proterozoic geologic evolution of the eastern Mojave Desert region, as defined by characteristics of its supracrustal rocks, granitoids, metamorphism, structural history, and Pb and Nd isotopic signature, contrasts sharply with other Proterozoic provinces of the southwestern United States. The oldest supracrustal rocks of the Mojave Desert region contain...
Source parameters for small events associated with the 1986 North Palm Springs, California, earthquake determined using empirical Green functions
J. Mori, A. Frankel
1990, Bulletin of the Seismological Society of America (80) 278-295
Using small events as empirical Green functions, which include path, site, and instrument effects on the P waveforms, source parameters were estimated for 25 ML 3.4 to 4.4 events associated with the 1986 North Palm Springs earthquake. The static stress drops ranged from 3 to 80 bars, for moments of...
A tomographic glimpse of the upper mantle source of magmas of the Jemez lineament, New Mexico
W. Spence, R.S. Gross
1990, Journal of Geophysical Research Solid Earth (95) 10829-10849
The 800-km-long Jemez lineament is the most active volcanic feature in the southwestern United States. It is the southeastern tectonic boundary of the Colorado Plateau and crosses the Rio Grande rift at the Jemez Mountains. The primary volcanism of the lineament is basaltic and has occurred in the last 4.5...
An evaluation of the accuracy of geomagnetic data obtained from an unattended, automated, quasi-absolute station
D.C. Herzog
1990, Physics of the Earth and Planetary Interiors (59) 112-118
A comparison is made of geomagnetic calibration data obtained from a high-sensitivity proton magnetometer enclosed within an orthogonal bias coil system, with data obtained from standard procedures at a mid-latitude U.S. Geological Survey magnetic observatory using a quartz horizontal magnetometer, a Ruska magnetometer, and a total field magnetometer. The orthogonal...
Comparison of methods to determine degree of pyritization
J. Leventhal, C. Taylor
1990, Geochimica et Cosmochimica Acta (54) 2621-2625
Degree of pyritization (DOP) is a measure of the ratio pyrite iron/(pyrite iron + reactive iron) that can be related to the depositional environment of a sediment. Several methods of DOP determination have been used but not systematically evaluated. The determination/extraction of reactive (usually acid soluble) iron is critical to...
Paleomagnetic rotations and the Cenozoic tectonics of the Cascade Arc, Washington, Oregon, and California
R.E. Wells
1990, Journal of Geophysical Research Solid Earth (95) 19409-19417
Paleomagnetic results from Cenozoic (62–12 Ma) volcanic rocks of the Cascade arc and adjacent areas indicate that moderate to large clockwise rotations are an important component of the tectonic history of the arc. Two mechanisms of rotation are suggested by the regional pattern of paleomagnetic rotations. The progressive increase in...
High spectral resolution reflectance spectroscopy of minerals
R. N. Clark, T. V. V. King, M. Klejwa, Gregg A. Swayze, N. Vergo
1990, Journal of Geophysical Research Solid Earth (95) 12653-12680
The reflectance spectra of minerals are studied as a function of spectral resolution in the range from 0.2 to 3.0 μm. Selected absorption bands were studied at resolving powers (λ/Δλ) as high as 2240. At resolving powers of approximately 1000, many OH‐bearing minerals show diagnostic sharp absorptions at the resolution...
Soil development on stable landforms and implications for landscape studies
J.W. Harden
1990, Geomorphology (3) 391-398
Soil development parameters include a wide variety of morphological, chemical, and mineralogical parameters, but some of the best indicators of time and surface stability are derived from field morphology. Over long time-spans, the most common time function for soil development is exponential...
Calculation of zero-offset vertical seismic profiles generated by a horizontal point force acting on the surface of an elastic half-space
Hsi-Ping Liu
1990, Bulletin of the Seismological Society of America (80) 832-856
Impulse responses including near-field terms have been obtained in closed form for the zero-offset vertical seismic profiles generated by a horizontal point force acting on the surface of an anelastic half-space. The method is based on the correspondence principle. Through transformation of variables, the Fourier transform of the elastic impulse...
Paleoclimatic implications of the high stand of Lake Lahontan derived from models of evaporation and lake level
S. Hostetler, L. V. Benson
1990, Climate Dynamics (4) 207-217
Based on previous climate model simulations of a split of the polar jet stream during the late Pleistocene, we hypothesize that (1) 20-13.5 ka BP, season-to-season variation in the latitudinal maximum of the jet stream core led to enhanced wetness in the Great Basin, and (2) after 13.5 ka BP,...
UPb ages of zircon rims: A new analytical method using the air-abrasion technique
J. N. Aleinikoff, D.L. Winegarden, M. Walters
1990, Chemical Geology: Isotope Geoscience Section (80) 351-363
We present a new technique for directly dating, by conventional techniques, the rims of zircons. Several circumstances, such as a xenocrystic or inherited component in igneous zircon and metamorphic overgrowths on igneous cores, can result in grains with physically distinct age components. Pneumatic abrasion has been previously shown by Krogh...
Radium and radon in Charlotte Harbor Estuary, Florida
R. L. Miller, T. F. Kraemer, B. F. McPherson
1990, Estuarine, Coastal and Shelf Science (31) 439-457
Radium-226 and 222Rn activities are greater in the estuarine waters of northern Charlotte Harbor and the lower tidal Peace and Myakka Rivers, Florida, than in either the freshwater reaches of the rivers or waters of the lower estuary and the Gulf of Mexico. The activity of 226Ra in the tidal rivers increases...
Organic tissues, graphite, and hydrocarbons in host rocks of the Rum Jungle Uranium Field, northern Australia
C.B. Foster, E. I. Robbins, Y. Bone
1990, Ore Geology Reviews (5) 509-523
The Rum Jungle Uranium field consists of at least six early Proterozoic deposits that have been mined either for uranium and/or the associated base and precious metals. Organic matter in the host rocks of the Whites Formation and Coomalie Dolomite is now predominantly graphite, consistent with the metamorphic history of...
Late cenozoic subduction complex of Sicily
F. Roure, D. G. Howell, C. Muller, I. Moretti
1990, Journal of Structural Geology (12) 259-266
Besides remnants of Hercynian deformations in the Peloritani nappe and of pre-Oligocene Alpine structures in the Troiani nappe, most compressive structures observed in the Sicilian accretionary wedge result from the late Cenozoic (Tortonian to Present) continental subduction of the Apulia...
Will the 1990’s be a decade of increasingly destructive natural disasters?
P. L. Boulle
1990, Earthquakes & Volcanoes (USGS) (22) 173-175
Today, there is a considerable body of knowledge about natural hazards that laso enables us to devise effective means to limit the damage they cause. Yet, the reality of the situation is that disasters are increasing in number worldwide, and their social and economic impacts are becoming more nad more...
Volcanism in the Sumisu Rift, I. Major element, volatile, and stable isotope geochemistry
A.G. Hochstaedter, J.B. Gill, M. Kusakabe, S. Newman, M. Pringle, B. Taylor, P. Fryer
1990, Earth and Planetary Science Letters (100) 179-194
A bimodal volcanic suite with KAr ages of 0.05–1.40 Ma was collected from the Sumisu Rift using alvin. These rocks are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, and provide a present day example of volcanism associated with...
Deep crustal structure of the Cascade Range and surrounding regions from seismic refraction and magnetotelluric data
William D. Stanley, Walter D. Mooney, Gary S. Fuis
1990, Journal of Geophysical Research (95) 19419-19438
Several regional seismic refraction and magnetotelluric (MT) profiles have been completed across the Cascade Range and surrounding geologic provinces in California, Oregon, and Washington. Analysis of three MT and two seismic refraction profiles in Oregon and a coincident MT and refraction profile in northern California show a high degree of...
Geothermal systems within the Mammoth Corridor in Yellowstone National Park and the adjacent Corwin Springs KGRA
Michael Sorey, Elizabeth Colvard, N.C. Sturchio
1990, Conference Paper, Transactions - Geothermal Resources Council
A study of potential impacts of geothermal development in the Corwin Springs KGRA north of Yellowstone Park on thermal springs within the Park is being conducted by the U.S. Geological Survey. Thermal waters in the KGRA and at Mammoth Hot Springs, located 13 km inside the Park boundary, are high...
Is the polar bear (Ursus maritimus) a hibernator? Continued studies on opioids and hibernation
David S. Bruce, Nancy K. Darling, Katheleen J. Seeland, Peter R. Oeltgen, Sita P. Nilekani, Steven C. Amstrup
1990, Pharmacology Biochemistry and Behavior (35) 705-711
Polar bear behavior and biochemistry suggest they may have the ability to hibernate year-round, even though this species is not considered to be a true hibernator. This observation, plus the discovery of a hibernation-induced trigger (HIT) in the blood of black bears, prompted the examination of polar bear blood collected...
Phytoplankton dynamics in three Rocky Mountain lakes, Colorado, USA
Diane M. McKnight, Richard L. Smith, J. Platt Bradbury, Jill Baron, Sarah A. Spaulding
1990, Arctic and Alpine Research (22) 264-274
In 1984 and 1985 seasonal changes in phytoplankton were studied in a system of three lakes in Loch Vale, Rocky Mountain National Park, Colorado. Three periods were evident: (1) A spring bloom, during snowmelt, of the planktonic diatom Asterionella formosa, (2) a mid-summer period of minimal algal abundance, and (3)...
Late Pleistocene and Holocene sedimentary facies on the Ebro continental shelf
J. Diaz, C.H. Nelson, J. H. Barber Jr., S. Giro
1990, Marine Geology (95) 333-352
Late Pleistocene—Holocene history of the Ebro continental shelf of northeastern Spain is recorded in two main sedimentary units: (1) a lower, transgressive unit that covers the shelf and is exposed on the outer shelf south of 40°40′N, and (2) an upper,...
Kilbuck terrane: Oldest known rocks in Alaska
S. E. Box, E. J. Moll-Stalcup, J. L. Wooden, J.Y. Bradshaw
1990, Geology (18) 1219-1222
The Kilbuck terrane in southwestern Alaska is a narrow, thin crustal sliver or flake of amphibolite facies orthogneiss. The igneous protolith of this gneiss was a suite of subduction-related platonic rocks. U-Pb data on zircons from trondhjemitic and granitic samples yield upper-intercept (igneous)...
Conducting field studies for testing pesticide leaching models
Charles N. Smith, Rudolph S. Parrish, David S. Brown
1990, International Journal of Environmental Analytical Chemistry (39) 3-21
A variety of predictive models are being applied to evaluate the transport and transformation of pesticides in the environment. These include well known models such as the Pesticide Root Zone Model (PRZM), the Risk of Unsaturated-Saturated Transport and Transformation Interactions for Chemical Concentrations Model (RUSTIC) and the Groundwater Loading Effects...
A Miocene termite nest from southern Argentina and its paleoclimatological implications
Thomas M. Bown, Jose H. Laza
1990, Ichnos: An International Journal for Plant and Animal Traces (1) 73-79
A Miocene termitarium attributable to the extant termite Syntermes (Isoptera: Termitidae, Nasutitermitinae) is the first fossil termite nest reported from South America and possibly the oldest record of the Isoptera from that continent. The fossil remains consist of most of the periphery of the subterranean portion of a single Syntermes nest, including chambers and...
Observations on the effects of irrigation water containing 3-trifluoromethyl-4-nitrophenol (TFM) on plants
P.A. Gilderhus
1990, Investigations in Fish Control 100
Abstract not submitted to date...
