Conference Papers
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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
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Links between tectonics, magmatism, and mineralization in the formation of Late Cretaceous porphyry systems in the Yukon-Tanana upland, eastern Alaska, USA
Cretaceous-Paleocene porphyry Cu(±Mo±Au) occurrences are scattered throughout the Yukon-Tanana upland in eastern Alaska. Known occurrences in eastern Alaska are poorly characterized, despite a resurgence in exploration. Porphyry deposits in the upland are emplaced into structurally complex metamorphic rocks representing a variety of tectonic environments, resulting in diverse alteration and minera
Authors
Douglas C. Kreiner, James V. Jones, Erin Todd, Christopher Holm-Denoma, Jonathan Caine, Jeff Benowitz
Updates to USGS national seismic hazard model (NSHM) and design ground motion maps for 2020 NEHRP recommended provisions
This presentation summarizes the proposed updates to earthquake design ground motions for the 2020 edition of the NEHRP Recommended Seismic Provisions, expected to be incorporated into the ASCE 7-22 Standard. The implications of these updates on the values of design ground motions for example locations in both conterminous and nonconterminous U.S. cities are shown and discussed.
Authors
Sanaz Rezaeian, Nicolas Luco
Snakehead fishes (Channa spp.) in the USA
The introduction of snakeheads from their origins in Asia is relatively recent to the conterminous United States with the first of many collections beginning in the late 1990s. For decades they have been commercially fished and aquacultured around the world for human food and, to a lesser degree, for the aquarium trade. Over a dozen snakehead species known to be of economic importance outside the
Authors
Amy Benson
Growth and energy budget of Northern Snakehead Channa argus in relation to ration
Northern Snakehead Channa argus weighing 188.54+13.80 g were fed live Oriental Weatherfish Misgurnus anguillicaudatus at five rations (starvation, 1, 2, 4% body weight per day and satiation) at 28 oC under laboratory conditions to determine its growth and energy budget in relation to ration. The specific growth rate increased linearly with increasing ration and food conversion efficiencies also te
Authors
Jiashou Liu, Tangling Zhang, Duane Chapman
Formation mechanisms of quartz veins in orogenic gold deposits: Insights from Grass Valley, California, USA
The orogenic gold veins of Grass Valley, California, USA, compose the historically richest lode gold district in the North American Cordillera. Petrographically, the veins exhibit a range of primary textural relationships allowing the reconstruction of the paragenetic sequence of mineral formation. Two generations of quartz are distinguished by optical cathodoluminescence microscopy and fluid incl
Authors
Ryan Taylor, Thomas Monecke, T. James Reynolds
Geochemistry of hematite veins in IOA-IOCG deposits of SE Missouri, USA: Relation to felsic magmatism and caldera lakes
The paragenesis, textures, and chemical compositions of secondary hematite in regional potassic altered rhyolites, four IOA deposits, the sedimentary iron deposit at Pilot Knob and the Boss IOCG deposit in SE Missouri were determined and compared to primary magnetite from the IOA and IOCG deposits. Magnetite is composed of elements characteristics of mafic to intermediate intrusions whereas hemati
Authors
Corey J. Meighan, Albert H. Hofstra, Erin E. Marsh, Heather A. Lowers, Alan Koenig
Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions
The paragenesis, textures, and chemical compositions of magnetite in two mafic to intermediate intrusions and four IOA deposits in SE Missouri were studied to discriminate between igneous and hydrothermal sources. In this study, we found that replacement magnetite with mineral inclusion-rich cores yields erroneously high Ti, Al, Si, Mg, and Mn contents as determined by EMP and LA-ICP-MS due to ru
Authors
Corey J. Meighan, Albert H. Hofstra, David Adams, Erin E. Marsh, Heather A. Lowers, Alan Koenig
Developing a precision irrigation framework to facilitate smallholder dry-season farming in developing countries: A case study in northern Ghana
Changing climate has resulted in increasingly unreliable weather patterns with prolonged dry-seasons in some parts of Sub-Saharan Africa. Food production in these areas is under threat because the people depend mostly on rain-fed farming. Enabling dry-season farming, in light of the prolonged dry-seasons, is central to sustainable food production and poverty alleviation in these areas. Efficient w
Authors
Jeremy M Fontaine, Joseph Fentzke, Erasmus K Oware, Eric Doe, Samuel Guug, John W. Lane
The effect of resolution on terrain feature extraction
Recent increase in the production of high-resolution digital elevation models (DEMs) from lidar data has led to interest in their use for terrain mapping. Although the impact of different resolutions has been studied relative to terrain characteristics like roughness, slope and curvature, its relationship to the extraction of terrain features remains unclear. To address this question, this study t
Authors
Samantha Arundel, Wenwen Li, Xiran Zhou
A physically based method of combining ADCP velocity data with point samples to compute suspended-sand discharge -- Application to the Rhone River, France
Measuring suspended-sand flux in rivers is a challenge since sand concentrations are highly variable in time and space throughout a river cross section. Most of the present methodologies rely on point or depth-integrated sampling (Nolan et al., 2005, Topping et al., 2016). The standard method estimates mean concentration and multiply it by discharge to compute the suspended-sand discharge. Here, w
Authors
Guillaume Dramais, Benoit Camenen, Jerome Le Coz, David Topping, Christophe Peteuil, Gilles Pierrefeu
Measuring suspended sediment in sand-bedded rivers using down-looking acoustic doppler current profilers
The use of side-looking acoustic Doppler velocity meters (ADVMs) to estimate fluvial
suspended-sediment concentrations (SSC) has become more operational by the U.S. Geological Survey in recent years; however, direct transfer of these techniques to down-looking acoustic Doppler current profilers (ADCPs) currently is not widely feasible. Key assumptions in the sidelooking ADVM method related to sedi
Authors
Molly S. Wood, Ricardo N. Szupiany, Justin A. Boldt, Timothy D. Straub, Marian M. Domanski
US Costal Research Program: Fostering academic research
The US Coastal Research Program (USCRP) was founded in 2016 through a grassroots initiative of scientists, researchers, and practitioners to address nearshore coastal research priorities of greatest relevance to coastal communities and build a skilled US coastal workforce. The USCRP supports academic research to address challenges identified through thematic workshops and pair academic researchers
Authors
Julie Dean Rosati, Nicole Elko, Hilary F Stockdon, Jeff Lillycrop, Mary Cialone