UScholar Works
 
Filters: Department: "Geology & Geophysics" Collection: "ir_uspace" Year End: 2006
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CreatorTitleDescriptionSubjectDate
1 Zhdanov, Michael S.3-D magnetic inversion with data compression and image focusingWe develop a method of 3-D magnetic anomaly inversion based on traditional Tikhonov regularization theory. We use a minimum support stabilizing functional to generate a sharp, focused inverse image. An iterative inversion process is constructed in the space of weighted model parameters that acce...2002-01-01
2 Brown, Francis HaroldA summary of the geology, geochemistry, and geophysics of the Roosevelt Hot Springs thermal area, Utah1978
3 Brown, Francis HaroldChronologyThe boundaries of the Lower Omo Basin have been mapped by Fuchs (1939) and by Butzer (1970, 1971) in a general way. The structural features and physiography of the eastern and central part of the Lower Omo Basin are best expressed on the maps of Davidson et al. (1973). Walsh and Dodson (1969) have m...1983
4 Jewell, PaulCirculation, salinity, and dissolved oxygen in the Cretaceous North American seawayCritical paleoceanographic problems regarding the maximum transgressive phase of the Cretaceous North American seaway have been studied with a three-dimensional ocean circulation model. Four simulations employing minimum and maximum solar insolation winds from the Cretaceous and a wide range of pre...Cretaceous North American Seaway1996
5 Chapman, David S.; Harris, Robert N.Climate change in India inferred from geothermal observationsTemporal variations in surface ground temperature impart a signal to the subsurface thermal regime that is captured in borehole temperature-depth profiles. Seventy temperature-depth profiles in India, located between 12o and 28oN, are analyzed to infer past changes in ground temperature.Climate change; Borehole temperatures; Surface ground temperature; Surface air temperature; Geothermal observations; India2002
6 Zhdanov, MichaelContraction integral equation method in three-dimensional electromagnetic modelingThe integral equation method has been proven to be an efficient tool to model threedimensional electromagnetic problems . Owing to the full linear system to be solved, the method has been considered effective only in the case of models consisting of a strongly limited number of cells. However, recen...2002-01-01
7 Jewell, PaulControls of tufa development in Pleistocene Lake Bonneville, UtahProminent tufa localities along the Provo level (∼14,000 14C yr B.P.) shoreline in Pleistocene Lake Bonneville have been characterized in detail. Three types of tufa are recognized: capping tufa, beachrock, and capping tufa over beachrock. Capping tufa and beachrock are end members of a continuum ...Tufa; Pleistocene; Pluvial lakes2006
8 Brown, Francis HaroldCorrelation of tephra layers from the Western Rift Valley (Uganda) to the Turkana Basin (Ethiopia/Kenya) and the Gulf of AdenFour volcanic ashes have been mapped in Albertine Group strata (Warwire, Kaiso Village and Nyabusosi Formations) Western Rift Valley, Uganda. Three of these tuffs have geochemical fingerprints similar to tuffs in the Turkana Basin (Ethiopia, Kenya), in Afar (Ethiopia) and the Gulf of Aden, permitti...1991
9 Zhdanov, MichaelCross-well electromagnetic imaging in three dimensionsIn this paper, we develop a new technique for 3D cross-well electromagnetic tomography, based on an EM borehole survey consisting of a moving vertical magnetic dipole transmitter, located in one or several boreholes, and a tri-axial induction receiver, located in the other boreholes. The method is b...2003
10 Jarrard, Richard D.Data report: high-resolution mineralogy for leg 199 based on reflectance spectroscopy and physical propertiesDuring Ocean Drilling Program Leg 199 in the equatorial Pacific, visible and near-infrared spectroscopy (VNIS) was used to measure the reflectance spectra (350?2500 nm) of 1343 sediment samples. Reflectance spectra were also measured for a suite of 60 samples of known mineralogy, thereby providing a...2004
11 Brown, Francis HaroldDatingThere are basically three lines of investigation that are involved in geochronology ? the dating of rocks and other earth materials. First, there are the physical and chemical dating methods which give us numerical estimates of age. Second, there is the reconstruction of the order of events in sec...1984
12 Jarrard, Richard D.Electrical properties of basalts from Sites 768 and 770Conductivity of 54 basalt samples from ODP Sites 768 and 770 was measured as a function of temperature and fluid salinity. Porosity was also measured for all samples, and cation exchange capacity was measured for 46 of the samples. Porosity measurements indicated that porosity is underestimated fo...1991
13 Zhdanov, Michael S.Electromagnetic inversion using quasi-linear approximationThree-dimensional electromagnetic inversion continues to be a challenging problem in electrical exploration. We have recently developed a new approach to the solution of this problem based on quasi-linear approximation of a forward modeling operator. It generates a linear equation with respect to ...Quasi-linear approximation; Electromagnetic inversion2000
14 Brown, Francis HaroldThe evolution of neogene terrestrial ecosystems in EuropeThe Pliocene-Pleistocene chronology of hominid and other vertebrate evolution in East Africa is largely constrained by isotopic dating and regional intercorrelation of volcanic ash layers. Some eruptions were of sufficient magnitude or duration that their widespread tephra dispersal defines a serie...1999
15 Chapman, David S.Exhumation of the central Wasatch Mountains, Utah: 1, Patterns and timing of exhumation deduced from low-temperature thermochronology dataThe Wasatch Mountains are often cited as an example of normal fault growth and footwall flexure. They represent a tilted footwall at the edge of the Basin and Range extensional province, a major rift basin. Thus understanding the detailed spatial and elevation changes in coupled thermochronometer da...Uplift; Exhumation; Wasatch Fault; Wasatch Mountains; Utah; Helium dating; Fission track; Tectonophysics; Extensional tectonics; Geothermal observations2002
16 Chapman, David S.Exhumation of the central Wasatch Mountains, Utah: 2, thermokinematic model of exhumation, erosion, and thermochronometer interpretationThe Wasatch fault is a ~370 km long normal fault in Utah that marks the boundary between the stable Colorado Plateau to the east and the extending Basin and Range to the west. Understanding the thermokinematic evolution of this fault can provide insights into intracontinental extensional tectonics a...Uplift; Exhumation; Wasatch Fault; Wasatch Mountains; Utah; Helium dating; Fission track; Tectonophysics; Extensional tectonics; Geothermal observations2002
17 Zhdanov, Michael S.Fast numerical modeling of multitransmitter electromagnetic data using multigrid quasi-linear approximationMultitransmitter electromagnetic (EM) surveys are widely used in remote-sensing and geophysical exploration. The interpretation of the multitransmitter geophysical data requires numerous three-dimensional (3-D) modelings of the responses of the receivers for different geoelectrical models of comple...Multitransmitter electromagnetic data; Numerical modeling; Multigrid quasi-linear approximation; Quasilinear approximation; geophysical exploration; 3-D modeling2006-06
18 Zhdanov, Michael S.Focusing geophysical inversion imagesA critical problem in inversion of geophysical data is developing a stable inverse problem solution that can simultaneously resolve complicated geological structures. The traditional way to obtain a stable solution is based on maximum smoothness criteria. This approach, however, provides smoothe...Focusing; Geophysical inversion images; Minimum gradient support functionals; MGS1999
19 Fernandez, Diego P.Formulation for the static permittivity of water and steam at temperatures from 238 K to 873 K at pressures up to 1200 MPa, including derivatives and Debye- Hückel coefficientsA new formulation is presented of the static relative permittivity or dielectric constant of water and steam, including supercooled and supercritical states. The range is from 238 K to 873 K, at pressures up to 1200 MPa. The formulation is based on the ITS-90 temperature scale. It correlates a selec...Static relative permittivity; Dielectric constant1997
20 Jarrard, Richard D.Geochemical results from wireline logs in the Celebes Sea, Sites 767 and 770 of Leg 124Geochemical well logs were obtained at ODP Sites 767 and 770 in the Celebes Sea. The log data obtained at sea have been corrected for borehole size changes, the effects of drilling fluids, and logging-speed variations. The processed logs are then used to calculate the amounts of the three major ra...1991
21 Jewell, PaulGeochemical variations in an alpine lake and watershed underlain by siliciclastic bedrock, Uinta Mountains, UtahA small watershed which includes several small lakes in the Uinta Mountains of northern Utah is underlain by monolithologic Precambrian siliciclastic rock with extremely limited buffering capacity. In spite of this, s\ stematic spatial and temporal variations in alkalinity, pH, and major elements oc...1998-01-01
22 Jewell, PaulGeochemistry and paleoceanographic setting of Central Nevada bedded baritesThe bedded barite deposits of central Nevada are hosted by rocks of the Roberts Mountains allochthon and constitute the largest barite reserves in North America. Detailed geochemical studies of three barite deposits in the Devonian Slaven Chert indicate that rocks surrounding the barite have elevate...Bedded barites; Roberts Mountains allochthon; Late Devonian1991
23 Brown, Francis HaroldGeological development of the Omo-Turkana Basin during the pliocene and pleistocene epochsPliocene and Pleistocene deposits of the Omo-Turkana Basin extend from 6?N latitude to about 2?N latitude (-450 km), and laterally from about 35.5?E to 36.5?E. Sediments are brought to the basin by the Omo River which rises in Ethiopia, and by the Turkwel and Kerio Rivers which rise in Kenya and Uga...2004
24 Jewell, PaulGeology and geothermal potential North of Wells, NevadaThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, ...Tertiary sediments; Siltstones; Conglomerates; Lithologies; Well logs; Aquifers; Step faults1982-01-01
25 Jewell, PaulThe geology and geothermal setting of the Magic Reservoir Area, Blaine and Camas Counties, IdahoThe Magic Reservoir area straddles the Blaine- Camas county line in south-central Idaho, along the northern boundary of the central Snake River Plain. The rocks exposed at Magic Reservoir include a 5.8- million-year-old rhyolite flow, the Pliocene Square Mountain Basalt, multiple cooling units ...1982
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