Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2354
Impact of mine and natural sources of mercury on water, sediment, and biota in Harley Gulch adjacent to the Abbott-Turkey Run mine, Lake County, California
Executive SummaryStable-isotope data indicate that there are three sources of water that effect the composition and Hg concentration of waters in Harley Gulch: (1) meteoric water that dominates water chemistry during the wet season; (2) thermal water effluent from the Turkey Run mine that effects the chemistry at sample site HG1; and (3) cold connate groundwater that dominates water chemistry duri
Authors
James J. Rytuba, Roger L. Hothem, Brianne E. Brussee, Daniel N. Goldstein
Chronology, sedimentology, and microfauna of groundwater discharge deposits in the central Mojave Desert, Valley Wells, California
During the late Pleistocene, emergent groundwater supported persistent and long-lived desert wetlands in many broad valleys and basins in the American Southwest. When active, these systems provided important food and water sources for local fauna, supported hydrophilic and phreatophytic vegetation, and acted as catchments for eolian and alluvial sediments. Desert wetlands are represented in the ge
Authors
Jeffrey S. Pigati, David M. Miller, Jordon E. Bright, Shannon Mahan, Jeffrey C. Nekola, James B. Paces
Aeromagnetic anomalies over faulted strata
High-resolution aeromagnetic surveys are now an industry standard and they commonly detect anomalies that are attributed to faults within sedimentary basins. However, detailed studies identifying geologic sources of magnetic anomalies in sedimentary environments are rare in the literature. Opportunities to study these sources have come from well-exposed sedimentary basins of the Rio Grande rift in
Authors
V. J. S. Grauch, Mark R. Hudson
A trans-dimensional Bayesian Markov chain Monte Carlo algorithm for model assessment using frequency-domain electromagnetic data
A meaningful interpretation of geophysical measurements requires an assessment of the space of models that are consistent with the data, rather than just a single, ‘best’ model which does not convey information about parameter uncertainty. For this purpose, a trans-dimensional Bayesian Markov chain Monte Carlo (MCMC) algorithm is developed for assessing frequencydomain electromagnetic (FDEM) data
Authors
Burke J. Minsley
Notes on interpretation of geophysical data over areas of mineralization in Afghanistan
Afghanistan has the potential to contain substantial metallic mineral resources. Although valuable mineral deposits have been identified, much of the country’s potential remains unknown. Geophysical surveys, particularly those conducted from airborne platforms, are a well-accepted and cost-effective method for obtaining information on the geological setting of a given area. This report summarizes
Authors
Benjamin J. Drenth
The influence of stream channels on distributions of Larrea tridentata and Ambrosia dumosa in the Mojave Desert, CA, USA: Patterns, mechanisms and effects of stream redistribution
Drainage channels are among the most conspicuous surficial features of deserts, but little quantitative analysis of their influence on plant distributions is available. We analysed the effects of desert stream channels (‘washes’) on Larrea tridentata and Ambrosia dumosa density and cover on an alluvial piedmont in the Mojave Desert, based on a spatial analysis of transect data encompassing a total
Authors
S. Schwinning, D.R. Sandquist, D. M. Miller, D. R. Bedford, S. L. Phillips, J. Belnap
Metagenomic analysis of a permafrost microbial community reveals a rapid response to thaw
Permafrost contains an estimated 1672 Pg carbon (C), an amount roughly equivalent to the total currently contained within land plants and the atmosphere1,2,3. This reservoir of C is vulnerable to decomposition as rising global temperatures cause the permafrost to thaw2. During thaw, trapped organic matter may become more accessible for microbial degradation and result in greenhouse gas emissions4,
Authors
R. MacKelprang, M. P. Waldrop, K.M. Deangelis, M.M. David, K.L. Chavarria, S.J. Blazewicz, E.M. Rubin, J.K. Jansson
Spatial mapping of mineralization with manganese-enhanced magnetic resonance imaging
Paramagnetic manganese can be employed as a calcium surrogate to sensitize the magnetic resonance imaging (MRI) technique to the processing of calcium during the bone formation process. At low doses, after just 48h of exposure, osteoblasts take up sufficient quantities of manganese to cause marked reductions in the water proton T1 values compared with untreated cells. After just 24h of exposure, 2
Authors
I.E. Chesnick, J.A. Centeno, T.I. Todorov, A.E. Koenig, K. Potter
Hydrothermal alteration of the Late Eocene Caetano ash-flow caldera, north-central Nevada: A field and ASTER remote sensing study
Geologic mapping and analysis of ASTER remote sensing data were used to define the effects of a large hydrothermal system in the 12–18 by 22 km Caetano caldera. The caldera formed at ~33.8Ma during eruption of >1100km3 of the rhyolitic Caetano Tuff that left a 1 km deep basin which was partly filled by a lake. Magma resurgence resulted in shallow(<1 km) emplacement of the Redrock Canyon granite po
Authors
David John, Barnaby W. Rockwell, Christopher D. Henry, Joseph Colgan
Erosion of tilted fault blocks and deposition of coarse sediments in half-graben basins during late stages of extension: Gold Butte area, Basin and Range Province
The provenance and stratigraphic architecture of basin-filling Miocene sediments around the Gold Butte area, southern Nevada, and adjacent highlands record the erosion of fault blocks that progressively tilted during extension. This study focuses especially on upper Miocene correlatives of the red sandstone unit and the Muddy Creek Formation that were deposited during waning stages of extension. U
Authors
Keith A. Howard, Sue Beard, M. A. Kuntz, Michael J. Kunk, Andrei M. Sarna-Wojcicki, M. E. Perkins, Ivo Lucchitta
Archeomagnetic dating in western North America: An updated reference curve based on paleomagnetic and archeomagnetic data sets
[1] A robust database of paleomagnetic (PM) and archeomagnetic (AM) data for western North America covering the past 4 millennia is assembled from three data sets: (1) published PM data for dated lava flows, (2) recently published AM data generated by R. L. DuBois, and (3) published AM data generated by J. L. Eighmy. Chronologic information for the AM data sets has been reassessed, and the data po
Authors
Jonathan T. Hagstrum, Eric Blinman
Rainfall infiltration-induced landslides
Unfavorable groundwater conditions are often the determining factor in triggering landslides. Whereas regional hydrogeology typically determines overall groundwater conditions, surficial rainfall infiltration into slopes also drives potential instability.
Authors
Brian D. Collins, Dobroslav Znidarcic