Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2350
Geochronology and paleoenvironment of pluvial Harper Lake, Mojave Desert, California, USA
Accurate reconstruction of the paleo-Mojave River and pluvial lake (Harper, Manix, Cronese, and Mojave) system of southern California is critical to understanding paleoclimate and the North American polar jet stream position over the last 500 ka. Previous studies inferred a polar jet stream south of 35°N at 18 ka and at ~ 40°N at 17–14 ka. Highstand sediments of Harper Lake, the upstream-most pluv
Authors
Anna L. Garcia, Jeffrey R. Knott, Shannon Mahan, Jordan Bright
Data-driven modeling of background and mine-related acidity and metals in river basins
A novel application of self-organizing map (SOM) and multivariate statistical techniques is used to model the nonlinear interaction among basin mineral-resources, mining activity, and surface-water quality. First, the SOM is trained using sparse measurements from 228 sample sites in the Animas River Basin, Colorado. The model performance is validated by comparing stochastic predictions of basin-al
Authors
Michael J Friedel
Petrologic, tectonic, and metallogenic evolution of the southern segment of the ancestral Cascades magmatic arc, California and Nevada
Ongoing arc magmatism along western North America was preceded by ancestral arc magmatism that began ca. 45 Ma and evolved into modern arc volcanism. The southern ancestral arc segment, active from ca. 30 to 3 Ma, adjoins the northern segment in northern California across a proposed subducted slab tear. The east edge of the Walker Lane approximates the east edge of the southern arc whose products,
Authors
Edward A. du Bray, David John, Brian L. Cousens
ASARCO Incorporated’s Car Project, 1990-94, western Gabbs Valley, Mineral Co., Nevada: precious metal exploration transitioned to geothermal exploration
No abstract available.
Authors
Peter G. Vikre, Fleetwood Koutz
The importance of mineralogical input into geometallurgy programs
Mineralogy is the link between ore formation and ore extraction. It is the most fundamental component of geomet programs, and the most important aspect of a life-of-project approach to mineral resource projects. Understanding orebodies is achieved by understanding the mineralogy
and texture of the materials, throughout the process, because minerals hold the information required to unlock the valu
Authors
K. Olson Hoal, J.D. Woodhead, Kathleen S. Smith
Geochemistry of soils from the San Rafael Valley, Santa Cruz County, Arizona
This study was conducted to determine whether surficial geochemical methods can be used to identify subsurface mineraldeposits covered by alluvium derived from surrounding areas. The geochemical investigation focused on an anomalous geo-physical magnetic high located in the San Rafael Valley in Santa Cruz County, Arizona. The magnetic high, inferred to be asso-ciated with a buried granite intrusio
Authors
Helen W. Folger, Floyd Gray
Paleomagnetic contributions to the Klamath Mountains terrane puzzle-a new piece from the Ironside Mountain batholith, northern California
We obtained paleomagnetic samples from six sites within the Middle Jurassic Ironside Mountain batholith (~170 Ma), which constitutes the structurally lowest part of the Western Hayfork terrane, in the Klamath Mountains province of northern California and southern Oregon. Structural attitudes measured in the coeval Hayfork Bally Meta-andesite were used to correct paleomagnetic data from the bathol
Authors
Edward A. Mankinen, C. Sherman Grommé, W. Porter Irwin
Principal facts and an approach to collecting gravity data using near-real-time observations in the vicinity of Barstow, California
A gravity survey was done in the vicinity of Barstow, California, in which data were processed and analyzed in the field. The purpose of the data collection was to investigate possible changes in gravity across mapped Quaternary faults and to improve regional gravity coverage, adding to the existing national gravity database. Data were collected, processed, analyzed, and interpreted in the field i
Authors
G. Phelps, C. Cronkite-Ratcliff, L. Klofas
Magnetotelluric survey to locate the Archean-Proterozoic suture zone in the northeastern Great Basin, Nevada, Utah, and Idaho
North-central Nevada contains a large amount of gold in linear belts, the origin of which is not fully understood. During July 2008, September 2009, and August 2010, the U.S. Geological Survey, as part of the Assessment Techniques for Concealed Mineral Resources project, collected twenty-three magnetotelluric soundings along two profiles in Box Elder County, Utah; Elko County, Nevada; and Cassia,
Authors
Jay A. Sampson, Brian D. Rodriguez
Crustal-scale recycling in caldera complexes and rift zones along the Yellowstone hotspot track: O and Hf isotopic evidence in diverse zircons from voluminous rhyolites of the Picabo volcanic field, Idaho
Rhyolites of the Picabo volcanic field (10.4–6.6 Ma) in eastern Idaho are preserved as thick ignimbrites and lavas along the margins of the Snake River Plain (SRP), and within a deep (>3 km) borehole near the central axis of the Yellowstone hotspot track. In this study we present new O and Hf isotope data and U–Pb geochronology for individual zircons, O isotope data for major phenocrysts (quartz,
Authors
Dana L. Drew, Ilya N. Bindeman, Kathryn E. Watts, Axel K. Schmitt, Bin Fu, Michael McCurry
A non-destructive method for dating human remains
The skeletal remains of several Native Americans were recovered in an eroded state from a creek bank in northeastern New Mexico. Subsequently stored in a nearby museum, the remains became lost for almost 36 years. In a recent effort to repatriate the remains, it was necessary to fit them into a cultural chronology in order to determine the appropriate tribe(s) for consultation pursuant to the Nati
Authors
Warren K. Lail, David Sammeth, Shannon Mahan, Jason Nevins
Tackling “boundary faults” across the Alaska-Yukon border: a report from the field
One day in late May, a team of geologists from
two countries and four different organizations got
together in a remote corner of the Yukon Territory
to try to rectify a mapping discrepancy called a
“boundary fault.”
Authors
Rick Saltus