Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2350
Magmatic ore deposits in layered intrusions - Descriptive model for reef-type PGE and contact-type Cu-Ni-PGE deposits
Layered, ultramafic to mafic intrusions are uncommon in the geologic record, but host magmatic ore deposits containing most of the world's economic concentrations of platinum-group elements (PGE) (figs. 1 and 2). These deposits are mined primarily for their platinum, palladium, and rhodium contents (table 1). Magmatic ore deposits are derived from accumulations of crystals of metallic oxides, or i
Authors
Michael L. Zientek
Spatial distribution of landslides triggered from the 2007 Niigata Chuetsu–Oki Japan Earthquake
Understanding the spatial distribution of earthquake-induced landslides from specific earthquakes provides an opportunity to recognize what to expect from future events. The July 16, 2007 Mw 6.6 (MJMA 6.8) Niigata Chuetsu–Oki Japan earthquake triggered hundreds of landslides in the area surrounding the coastal city of Kashiwazaki and provides one such opportunity to evaluate the impacts of an offs
Authors
Brian D. Collins, Robert E. Kayen, Yasuo Tanaka
Active transtensional intracontinental basins: Walker Lane in the western Great Basin
The geometry and dimensions of sedimentary basins within the Walker Lane are a result of Plio-Pleistocene transtensive deformation and partial detachment of the Sierra Nevada crustal block from the North American plate. Distinct morpho-tectonic domains lie within this active transtensive zone. The northeast end of the Walker Lane is partly buried by active volcanism of the southern Cascades, and a
Authors
Angela S. Jayko, Marcus Bursik
An unusual molluscan faunule from the upper part of the Monterey Formation (middle to late Miocene) in Arroyo Seco, Monterey County, central California
No abstract available.
Authors
Charles L. Powell
Using hydrogeology to identify the source of groundwater to Montezuma Well, a natural spring in central Arizona: part 1
Montezuma Well is a natural spring located within a “sinkhole” in the desert environment of the Verde Valley in Central Arizona. It is managed by the National Park Service as part of Montezuma Castle National Monument. Because of increasing development of groundwater in the area, this research was undertaken to better understand the sources of groundwater to Montezuma Well. The use of well logs an
Authors
Raymond H. Johnson, Ed H. DeWitt, L. Rick Arnold
Sulfur, carbon, hydrogen, and oxygen isotope geochemistry of the Idaho cobalt belt
Cobalt-copper ± gold deposits of the Idaho cobalt belt, including the deposits of the Blackbird district, have been analyzed for their sulfur, carbon, hydrogen, and oxygen isotope compositions to improve the understanding of ore formation. Previous genetic hypotheses have ranged widely, linking the ores to the sedimentary or diagenetic history of the host Mesoproterozoic sedimentary rocks, to Meso
Authors
Craig A. Johnson, Arthur A. Bookstrom, John F. Slack
Petroleum prospectivity of the Canada Basin, Arctic Ocean
Reconnaissance seismic reflection data indicate that Canada Basin is a >700,000 sq. km. remnant of the Amerasia Basin of the Arctic Ocean that lies south of the Alpha-Mendeleev Large Igneous Province, which was constructed across the northern part of the Amerasia Basin between about 127 and 89–83.5 Ma. Canada Basin was filled by Early Jurassic to Holocene detritus from the Beaufort–Mackenzie Delta
Authors
Arthur Grantz, Patrick E. Hart
Progress report geologic map of the Grouse Creek 30' x 60' quadrangle, and Utah part of the Jackpot 30' x 60' quadrangle, Box Elder County, Utah, and Cassia County, Idaho (Year 3 of 4);
No abstract available.
Authors
David M. Miller, Donald L. Clark, Michael L. Wells, Charles G. Oviatt, Tracey J. Felger, Victoria R. Todd
Laboratory investigations of the effects of nitrification-induced acidification on Cr cycling in vadose zone material partially derived from ultramafic rocks
Sacramento Valley (California, USA) soils and sediments have high concentrations of Cr(III) because they are partially derived from ultramafic material. Some Cr(III) is oxidized to more toxic and mobile Cr(VI) by soil Mn oxides. Valley soils typically have neutral to alkaline pH at which Cr(III) is highly immobile. Much of the valley is under cultivation and is both fertilized and irrigated. A ser
Authors
Christopher T. Mills, Martin B. Goldhaber
SHRIMP U-Pb ages of xenotime and monazite from the Spar Lake red bed-associated Cu-Ag deposit, western Montana: Implications for ore genesis
Xenotime occurs as epitaxial overgrowths on detrital zircons in the Mesoproterozoic Revett Formation (Belt Supergroup) at the Spar Lake red bed-associated Cu-Ag deposit, western Montana. The deposit formed during diagenesis of Revett strata, where oxidizing metal-bearing hydrothermal fluids encountered a reducing zone. Samples for geochronology were collected from several mineral zones. Xenotime o
Authors
John N. Aleinikoff, Timothy S. Hayes, Karl V. Evans, Frank K. Mazdab, Renee M. Pillers, C. Mark Fanning
Duststones on Mars: Source, transport, deposition and erosion
Dust is an abundant material on Mars, and there is strong evidence that it is a contributor to the rock record as “duststone,” analogous in many ways to loess on Earth. Although a common suite of dust formation mechanisms has operated on the two planets, fundamental differences in environments and geologic histories have resulted in vastly different weighting functions, causing distinct deposition
Authors
Nathan T. Bridges, Daniel R. Muhs
Field experiment provides ground truth for surface nuclear magnetic resonance measurement
The need for sustainable management of fresh water resources is one of the great challenges of the 21st century. Since most of the planet's liquid fresh water exists as groundwater, it is essential to develop non-invasive geophysical techniques to characterize groundwater aquifers. A field experiment was conducted in the High Plains Aquifer, central United States, to explore the mechanisms governi
Authors
R. Knight, E. Grunewald, T. Irons, K. Dlubac, Y. Song, H.N. Bachman, B. Grau, D. Walsh, J.D. Abraham, J. Cannia