Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2354
Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot
Siletzia is a basaltic Paleocene and Eocene large igneous province in coastal Oregon, Washington, and southern Vancouver Island that was accreted to North America in the early Eocene. New U-Pb magmatic, detrital zircon, and 40Ar/39Ar ages constrained by detailed field mapping, global nannoplankton zones, and magnetic polarities allow correlation of the volcanics with the 2012 geologic time scale.
Authors
Ray Wells, David Bukry, Richard Friedman, Douglas Pyle, Robert Duncan, Peter J. Haeussler, Joe Wooden
By
Energy and Minerals Mission Area, Natural Hazards Mission Area, Energy Resources Program, Geomagnetism Program, Groundwater and Streamflow Information Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Geologic Hazards Science Center, Geology, Minerals, Energy, and Geophysics Science Center
Steady incision of Grand Canyon at the million year timeframe: A case for mantle-driven differential uplift
The Grand Canyon region provides an excellent laboratory to examine the interplay between river incision, magmatism, and the geomorphic and tectonic processes that shape landscapes. Here we apply U-series, Ar–Ar, and cosmogenic burial dating of river terraces to examine spatial variations in incision rates along the 445 km length of the Colorado River through Grand Canyon. We also analyze strath t
Authors
Ryan S. Crow, Karl Karlstrom, Andrew Darling, Laura Crossey, Victor Polyak, Darryl E. Granger, Yemane Asmerom, Brandon Schmandt
Modified expression for bulb-tracer depletion—Effect on argon dating standards
40Ar/39Ar geochronology depends critically on well-calibrated standards, often traceable to first-principles K-Ar age calibrations using bulb-tracer systems. Tracer systems also provide precise standards for noble-gas studies and interlaboratory calibration. The exponential expression long used for calculating isotope tracer concentrations in K-Ar age dating and calibration of 40Ar/39Ar age standa
Authors
Robert J. Fleck, Andrew T. Calvert
Porphyry copper assessment of eastern Australia
The U.S. Geological Survey (USGS) conducts national and global assessments of resources (mineral, energy, water, and biologic) to provide science in support of decision making. Mineral resource assessments provide syntheses of available information about where mineral deposits are known and suspected to occur in the Earth’s crust and which commodities may be present, together with estimates of amo
Authors
Arthur A. Bookstrom, Richard A. Len, Jane M. Hammarstrom, Gilpin R. Robinson, Michael L. Zientek, Benjamin J. Drenth, Subhash Jaireth, Pamela M. Cossette, John C. Wallis
Sediment-hosted gold deposits of the world: Database and grade and tonnage models
All sediment-hosted gold deposits (as a single population) share one characteristic—they all have disseminated micron-sized invisible gold in sedimentary rocks. Sediment-hosted gold deposits are recognized in the Great Basin province of the western United States and in China along with a few recognized deposits in Indonesia, Iran, and Malaysia. Three new grade and tonnage models for sediment-hoste
Authors
Vladimir I. Berger, Dan L. Mosier, James D. Bliss, Barry C. Moring
Using nuclear magnetic resonance and transient electromagnetics to characterise water distribution beneath an ice covered volcanic crater: The case of Sherman Crater Mt. Baker Washington.
Surface and laboratory Nuclear Magnetic Resonance (NMR) measurements combined with transient electromagnetic (TEM) data are powerful tools for subsurface water detection. Surface NMR (sNMR) and TEM soundings, laboratory NMR, complex resistivity, and X-Ray Diffraction (XRD) analysis were all conducted to characterise the distribution of water within Sherman Crater on Mt. Baker, WA. Clay rich rocks,
Authors
Trevor P. Irons, Kathryn Martin, Carol A. Finn, Benjamin R. Bloss, Robert Horton
Platinum-group elements in southern Africa: mineral inventory and an assessment of undiscovered mineral resources
The platinum-group elements, platinum, palladium, rhodium, ruthenium, iridium, and osmium, possess unique physical and chemical characteristics that make them indispensable to modern technology and industry. However, mineral deposits that are the main sources of these elements occur only in three countries in the world, raising concerns about potential disruption in mineral supply. Using informati
Authors
Michael L. Zientek, J. Douglas Causey, Heather L. Parks, Robert J. Miller
Cross-ecosystem impacts of stream pollution reduce resource and contaminant flux to riparian food webs
The effects of aquatic contaminants are propagated across ecosystem boundaries by aquatic insects that export resources and contaminants to terrestrial food webs; however, the mechanisms driving these effects are poorly understood. We examined how emergence, contaminant concentration, and total contaminant flux by adult aquatic insects changed over a gradient of bioavailable metals in streams and
Authors
Johanna M. Kraus, Travis S. Schmidt, David Walters, Richard B. Wanty, Robert E. Zuellig, Ruth E. Wolf
Bouse Formation in the Bristol basin near Amboy, California, USA
Limestone beds underlain and overlain by alluvial fan conglomerate near Amboy, California, are very similar in many respects to parts of the Bouse Formation, suggesting that an arm of the Pliocene Bouse water body extended across a wide part of the southern Mojave Desert. The deposits are north of the town of Amboy at and below an elevation of 290 m, along the northern piedmont of the Bristol “dry
Authors
David M. Miller, Robert E. Reynolds, Jordan E. Bright, Scott W. Starratt
Multi-elemental analysis of aqueous geological samples by inductively coupled plasma-optical emission spectrometry
Typically, 27 major, minor, and trace elements are determined in natural waters, acid mine drainage, extraction fluids, and leachates of geological and environmental samples by inductively coupled plasma-optical emission spectrometry (ICP-OES). At the discretion of the analyst, additional elements may be determined after suitable method modifications and performance data are established. Samples a
Authors
Todor I. Todorov, Ruth E. Wolf, Monique Adams
Three-dimensional distribution of igneous rocks near the Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska: constraints from regional-scale aeromagnetic data
Aeromagnetic data helped us to understand the 3D distribution of plutonic rocks near the Pebble porphyry copper deposit in southwestern Alaska, USA. Magnetic susceptibility measurements showed that rocks in the Pebble district are more magnetic than rocks of comparable compositions in the Pike Creek–Stuyahok Hills volcano-plutonic complex. The reduced-to-pole transformation of the aeromagnetic dat
Authors
Eric D. Anderson, Wei Zhou, Yaoguo Li, Murray W. Hitzman, Thomas Monecke, James R. Lang, Karen D. Kelley
Airborne geophysical surveys conducted in western Nebraska, 2010: contractor reports and data
This report contains three contractor reports and data files for an airborne electromagnetic survey flown from June 28 to July 7, 2010. The first report; “SkyTEM Survey: Nebraska, USA, Data” describes data aquisition and processing from a time-domain electromagnetic and magnetic survey performed by SkyTEM Canada, Inc. (the North American SkyTEM subsidiary), in western Nebraska, USA. Digital data f
Authors