Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2354
Mineral deposit densities for estimating mineral resources
Estimates of numbers of mineral deposits are fundamental to assessing undiscovered mineral resources. Just as frequencies of grades and tonnages of well-explored deposits can be used to represent the grades and tonnages of undiscovered deposits, the density of deposits (deposits/area) in well-explored control areas can serve to represent the number of deposits. Empirical evidence presented here in
Authors
Donald A. Singer
Structures controlling geothermal circulation identified through gravity and magnetic transects, Surprise Valley, California, northwestern Great Basin
No abstract available.
Authors
Jonathan M.G. Glen, Anne E. Egger, David A. Ponce
Axial high topography and partial melt in the crust and mantle beneath the western Galápagos Spreading Center
The hot spot-influenced western Galápagos Spreading Center (GSC) has an axial topographic high that reaches heights of ∼700 m relative to seafloor depth ∼25 km from the axis. We investigate the cause of the unusual size of the axial high using a model that determines the flexural response to loads resulting from the thermal and magmatic structure of the lithosphere. The thermal structure simulated
Authors
Tanya M. Blacic, Garrett Ito, Anjana K. Shah, Juan Pablo Canales, Jian Lin
Quickly erupted volcanic sections of the Steens Basalt, Columbia River Basalt Group: Secular variation, tectonic rotation, and the Steens Mountain reversal
The Steens Basalt, now considered part of the Columbia River Basalt Group (CRBG), contains the earliest eruptions of this magmatic episode. Lava flows of the Steens Basalt cover about 50,000 km2 of the Oregon Plateau in sections up to 1000 m thick. The large number of continuously exposed, quickly erupted lava flows (some sections contain over 200 flows) allows for small loops in the magnetic fiel
Authors
Nicholas A. Jarboe, Robert S. Coe, Paul R. Renne, Jonathan M. G. Glen, Edward A. Mankinen
Cyanide speciation at four gold leach operations undergoing remediation
Analyses have been made of 81 effluents from four gold leach operations in various stages of remediation to identify the most-persistent cyanide species. Total cyanide and weak acid-dissociable (WAD) cyanide were measured using improved methods, and metals known to form stable cyanocomplexes were also measured. Typically, total cyanide greatly exceeded WAD indicating that cyanide was predominantly
Authors
Craig A. Johnson, David J. Grimes, Reinhard W. Leinz, Robert O. Rye
Dissolved and labile concentrations of Cd, Cu, Pb, and Zn in the South Fork Coeur d'Alene River, Idaho: Comparisons among chemical equilibrium models and implications for biotic ligand models
In order to evaluate thermodynamic speciation calculations inherent in biotic ligand models, the speciation of dissolved Cd, Cu, Pb, and Zn in aquatic systems influenced by historical mining activities is examined using equilibrium computer models and the diffusive gradients in thin films (DGT) technique. Several metal/organic-matter complexation models, including WHAM VI, NICA-Donnan, and Stockho
Authors
Laurie S. Balistrieri, R.G. Blank
Origin and paleoclimatic significance of late Quaternary loess in Nebraska: Evidence from stratigraphy, chronology, sedimentology, and geochemistry
Loess is one of the most extensive surficial geologic deposits in midcontinental North America, particularly in the central Great Plains region of Nebraska. Last-glacial-age loess (Peoria Loess) reaches its greatest known thickness in the world in this area. New stratigraphic, geochronologic, mineralogic, and geochemical data yield information about the age and provenance of Peoria Loess, as well
Authors
Daniel R. Muhs, E. Arthur Bettis, John N. Aleinikoff, John P. McGeehin, Jossh Beann, Gary Skipp, Brian D. Marshall, Helen M. Roberts, William C. Johnson, Rachel Benton
Isotopic evidence for the diversity of late Quaternary loess in Nebraska: Glaciogenic and nonglaciogenic sources
Pb isotope compositions of detrital K-feldspars and U-Pb ages of detrital zircons are used as indicators for determining the sources of Peoria Loess deposited during the last glacial period (late Wisconsin, ca. 25–14 ka) in Nebraska and western Iowa. Our new data indicate that only loess adjacent to the Platte River has Pb isotopic characteristics suggesting derivation from this river. Most Peoria
Authors
John N. Aleinikoff, Daniel R. Muhs, E. Arthur Bettis, William C. Johnson, C. Mark Fanning, Rachel Benton
Limestone - A Crucial and Versatile Industrial Mineral Commodity
Limestone, as used by the minerals industry, is any rock composed mostly of calcium carbonate (CaCO3). Although limestone is common in many parts of the United States, it is critically absent from some. Limestone is used to produce Portland cement, as aggregate in concrete and asphalt, and in an enormous array of other products, making it a truly versatile commodity. Portland cement is essential t
Authors
James D. Bliss, Timothy S. Hayes, Greta J. Orris
Environmental factors affecting mercury in Camp Far West Reservoir, California, 2001-03
This report documents water quality in Camp Far West Reservoir from October 2001 through August 2003. The reservoir, located at approximately 300 feet above sea level in the foothills of the northwestern Sierra Nevada, California, is a monomictic lake characterized by extreme drawdown in the late summer and fall. Thermal stratification in summer and fall is coupled with anoxic conditions in the hy
Authors
Charles N. Alpers, A. Robin Stewart, Michael K. Saiki, Mark C. Marvin-DiPasquale, Brent R. Topping, Kelly M. Rider, Steven K. Gallanthine, Cynthia A. Kester, Robert O. Rye, Ronald C. Antweiler, John F. De Wild
Millimeter-scale geologic mapping using field spectroscopy techniques
No abstract available.
Authors
David C. Buesch, Daniel E. Ragona, Mark C. Helmlinger
Wild, scenic and rapid trip down the Colorado River trough: Desert Symposium field trip
This rapid trip will explore wild fluvial and tectonic events resulting in scenic and rugged topography. The extreme differences in elevation caused valleys to be choked by alluvium and incised by the Colorado River drainage system.
Authors
R. E. Reynolds, J. Faulds, P.K. House, Keith A. Howard, Daniel V. Malmon, C. F. Miller, P. A. Pearthree