Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2354
Geochemistry, petrography, and zircon U-Pb geochronology of Paleozoic metaigneous rocks in the Mount Veta area of east-central Alaska: implications for the evolution of the westernmost part of the Yukon-Tanana terrane
We report the results of new mapping, whole-rock major, minor, and trace-element geochemistry, and petrography for metaigneous rocks from the Mount Veta area in the westernmost part of the allochthonous Yukon–Tanana terrane (YTT) in east-central Alaska. These rocks include tonalitic mylonite gneiss and mafic metaigneous rocks from the Chicken metamorphic complex and the Nasina and Fortymile River
Authors
Cynthia Dusel-Bacon, Warren C. Day, John N. Aleinikoff
Development and application of a soil organic matter-based soil quality index in mineralized terrane of the Western US
Soil quality indices provide a means of distilling large amounts of data into a single metric that evaluates the soil’s ability to carry out key ecosystem functions. Primarily developed in agroecosytems, then forested ecosystems, an index using the relation between soil organic matter and other key soil properties in more semi-arid systems of the Western US impacted by different geologic mineraliz
Authors
S.W. Blecker, Lisa L. Stillings, M.C. Amacher, J.A. Ippolito, N.M. DeCrappeo
Miscellaneous geochemical data from waters in the Upper Animas River Watershed, Colorado
This report releases geochemistry data in waters from the upper Animas River watershed that have been analyzed by inductively coupled plasma–mass spectrometry. These samples were collected at various sites and at various dates (41 sites and 86 samples from 2008 to 2010). A main data table is provided and the text discusses the sampling methods and locations in relation to other published reports.
Authors
Raymond H. Johnson, Douglas B. Yager
Geological analysis of aeromagnetic data from southwestern Alaska: Implications for exploration in the area of the Pebble porphyry Cu-Au-Mo deposit
Aeromagnetic data are used to better understand the geology and mineral resources near the Late Cretaceous Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska. The reduced-to-pole (RTP) transformation of regional-scale aeromagnetic data shows that the Pebble deposit is within a cluster of magnetic anomaly highs. Similar to Pebble, the Iliamna, Kijik, and Neacola porphyry copper occurrences are
Authors
Eric D. Anderson, Murray W. Hitzman, Thomas Monecke, Paul A. Bedrosian, Anjana K. Shah, Karen D. Kelley
Identifying buried segments of active faults in the northern Rio Grande Rift using aeromagnetic, LiDAR,and gravity data, south-central Colorado, USA
Combined interpretation of aeromagnetic and LiDAR data builds on the strength of the aeromagnetic method to locate normal faults with significant offset under cover and the strength of LiDAR interpretation to identify the age and sense of motion of faults. Each data set helps resolve ambiguities in interpreting the other. In addition, gravity data can be used to infer the sense of motion for total
Authors
V. J. S. Grauch, Chester A. Ruleman
Application and evaluation of electromagnetic methods for imaging saltwater intrusion in coastal aquifers: Seaside Groundwater Basin, California
Developing effective resource management strategies to limit or prevent saltwater intrusion as a result of increasing demands on coastal groundwater resources requires reliable information about the geologic structure and hydrologic state of an aquifer system. A common strategy for acquiring such information is to drill sentinel wells near the coast to monitor changes in water salinity with time.
Authors
Vanessa Nenna, Daan Herckenrather, Rosemary Knight, Nick Odlum, Darcy McPhee
Correlation of geothermal springs with sub-surface fault terminations revealed by high-resolution, UAV-acquired magnetic data
There is widespread agreement that geothermal springs in extensional geothermal systems are concentrated at fault tips and in fault interaction zones where porosity and permeability are dynamically maintained (Curewitz and Karson, 1997; Faulds et al., 2010). Making these spatial correlations typically involves geological and geophysical studies in order to map structures and their relationship to
Authors
Jonathan M.G. Glen, A.E. Egger, C. Ippolito, N.Athens
Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation
As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hy
Authors
Andrew G. Hunt, Laura Stern, John W. Pohlman, Carolyn Ruppel, Richard J. Moscati, Gary P. Landis
Summary of 2012 reconnaissance field studies related to the petroleum geology of the Nenana Basin, interior Alaska
The Alaska Division of Geological & Geophysical Surveys (DGGS) recently initiated a multi-year review of the hydrocarbon potential of frontier sedimentary basins in Alaska (Swenson and others, 2012). In collaboration with the Alaska
Division of Oil & Gas and the U.S. Geological Survey we conducted reconnaissance field studies in two basins with recognized
natural gas potential—the Susitna basin
Authors
Marwan A. Wartes, Robert J. Gillis, Trystan M. Herriott, Richard G. Stanley, Kenneth P. Helmold, C. Shaun Peterson, Jeffrey A. Benowitz
Hydrocarbon-bearing sandstone in the Upper Jurassic Naknek Formation on the south shore of Kamishak Bay
The presence of an active petroleum system in Kamishak Bay is demonstrated by an outcrop of hydrocarbon-bearing
sandstone in the Upper Jurassic Naknek Formation near the south shore of the bay (fig. 1). The outcrop is about 140 km
southwest of Homer on a small, unnamed island near the mouth of the Douglas River (fig. 17). The existence of this outcrop was kindly reported to us by Les Magoon (U.S
Authors
Richard G. Stanley, Trystan M. Herriott, Kenneth P. Helmold, Robert J. Gillis, Paul G. Lillis
Reconnaissance studies of potential petroleum source rocks in the Middle Jurassic Tuxedni Group near Red Glacier, eastern slope of Iliamna Volcano
Previous geological and organic geochemical studies have concluded that organic-rich marine shale in the Middle Jurassic Tuxedni Group is the principal source rock of oil and associated gas in Cook Inlet (Magoon and Anders, 1992; Magoon, 1994; Lillis and Stanley, 2011; LePain and others, 2012; LePain and others, submitted). During May 2009 helicopter-assisted field studies, 19 samples of dark-colo
Authors
Richard G. Stanley, Trystan M. Herriott, David L. LePain, Kenneth P. Helmold, C. Shaun Peterson
Preliminary stratigraphy and facies analysis of the Upper Cretaceous Kaguyak Formation, including a brief summary of newly discovered oil stain, upper Alaska Peninsula
The Alaska Division of Geological and Geophysical Surveys has an ongoing program aimed at evaluating the Mesozoic forearc stratigraphy, structure, and petroleum systems of lower Cook Inlet. Most of our field studies have focused on the Jurassic component of the petroleum system[this report.] However, in late July and early August of 2012, we initiated a study of the stratigraphy and reservoir pote
Authors
Marwan A. Wartes, Paul L. Decker, Richard G. Stanley, Trystan M. Herriott, Kenneth P. Helmold, Robert J. Gillis