Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2354
Thermochronology of Cretaceous batholithic rocks in the northern Peninsular Ranges batholith, southern California: Implications for the Late Cretaceous tectonic evolution of southern California
The thermochronology for several suites of Mesozoic metamorphic and plutonic rocks collected throughout the northern Peninsular Ranges batholith (PRB) was studied as part of a collaborative isotopic study to further our understanding of the magmatic and tectonic history of southern California. These sample suites include: a traverse through the plutonic rocks across the northern PRB (N = 29), a tr
Authors
Daniel P. Miggins, Wayne R. Premo, Lawrence W Snee, Ross Yeoman, Nancy D. Naeaer, Charles W. Naeser, Douglas M. Morton
Preliminary isostatic residual gravity map of the Tremonton 30' x 60' quadrangle, Box Elder and Cache Counties, Utah, and Franklin and Oneida Counties, Idaho
A new isostatic residual gravity map of the Tremonton 30' x 60' quadrangle of Utah is based on compilation of preexisting data and new data collected by the Utah and U.S. Geological Surveys. Pronounced gravity lows occur over North Bay, northwest of Brigham City, and Malad and Blue Creek Valleys, indicating significant thickness of low-density Tertiary sedimentary rocks and deposits. Gravity highs
Authors
Victoria E. Langenheim, R.Q. Oaks, H. Willis, A.I. Hiscock, Bruce A. Chuchel, Jose J. Rosario, C.L. Hardwick
Segmentation of plate coupling, fate of subduction fluids, and modes of arc magmatism in Cascadia, inferred from magnetotelluric resistivity
Five magnetotelluric (MT) profiles have been acquired across the Cascadia subduction system and transformed using 2-D and 3-D nonlinear inversion to yield electrical resistivity cross sections to depths of ∼200 km. Distinct changes in plate coupling, subduction fluid evolution, and modes of arc magmatism along the length of Cascadia are clearly expressed in the resistivity structure. Relatively hi
Authors
Philip E. Wannamaker, Rob L. Evans, Paul A. Bedrosian, Martyn J. Unsworth, Virginie Maris, R. Shane McGary
Multielevation calibration of frequency-domain electromagnetic data
Systematic calibration errors must be taken into account because they can substantially impact the accuracy of inverted subsurface resistivity models derived from frequency-domain electromagnetic data, resulting in potentially misleading interpretations. We have developed an approach that uses data acquired at multiple elevations over the same location to assess calibration errors. A significant a
Authors
Burke J. Minsley, M. Andy Kass, Greg Hodges, Bruce D. Smith
Mapping saltwater intrusion in the Biscayne Aquifer, Miami-Dade County, Florida using transient electromagnetic sounding
Saltwater intrusion in southern Florida poses a potential threat to the public drinking-water supply that is typically monitored using water samples and electromagnetic induction logs collected from a network of wells. Transient electromagnetic (TEM) soundings are a complementary addition to the monitoring program because of their ease of use, low cost, and ability to fill in data gaps between wel
Authors
David V. Fitterman
Petrology and chemistry of the Green Acres gabbro complex near Winchester, Riverside County, California
The Cretaceous Green Acres layered igneous complex, northeast of Winchester, California, is composed of a suite of olivine- and hornblende-bearing gabbros in the Peninsular Ranges batholith within the Perris tectonic block. A consistent mineral assemblage is observed throughout the complex, but there is considerable textural and modal heterogeneity. Both preclude a consistent set of principles bas
Authors
Byron R. Berger
Geophysical investigations of the geologic and hydrothermal framework of the Pilgrim Springs Geothermal Area, Alaska
Pilgrim Hot Springs, located on the Seward Peninsula in west-central Alaska, is characterized by hot springs, surrounding thawed regions, and elevated lake temperatures. The area is of interest because of its potential for providing renewable energy for Nome and nearby rural communities. We performed ground and airborne geophysical investigations of the Pilgrim Springs geothermal area to identify
Authors
Jonathan M.G. Glen, Darcy McPhee, Paul A. Bedrosian
The Wallula fault and tectonic framework of south-central Washington, as interpreted from magnetic and gravity anomalies
The Yakima fold and thrust belt (YFTB) in central Washington has accommodated regional, mostly north-directed, deformation of the Cascadia backarc since prior to emplacement of Miocene flood basalt of the Columbia River Basalt Group (CRBG). The YFTB consists of two structural domains. Northern folds of the YFTB strike eastward and terminate at the western margin of a 20-mGal negative gravity anoma
Authors
Richard J. Blakely, Brian L. Sherrod, Craig S. Weaver, Ray Wells, Alan C. Rohay
Modeling the hydrogeophysical response of lake talik evolution
Geophysical methods provide valuable information about subsurface permafrost and its relation to dynamic hydrologic systems. Airborne electromagnetic data from interior Alaska are used to map the distribution of permafrost, geological features, surface water, and groundwater. To validate and gain further insight into these field datasets, we also explore the geophysical response to hydrologic simu
Authors
Burke J. Minsley, Tristan Wellman, Michelle Ann Walvoord, Andre Revil
The planning process
No abstract available.
Authors
Carol C. Russell, Kathleen S. Smith, Virginia T. McLemore
Width and dip of the southern San Andreas Fault at Salt Creek from modeling of geophysical data
We investigate the geometry and width of the southernmost stretch of the San Andreas Fault zone using new gravity and magnetic data along line 7 of the Salton Seismic Imaging Project. In the Salt Creek area of Durmid Hill, the San Andreas Fault coincides with a complex magnetic signature, with high-amplitude, short-wavelength magnetic anomalies superposed on a broader magnetic anomaly that is at l
Authors
Victoria E. Langenheim, Noah D. Athens, Daniel S. Scheirer, Gary S. Fuis, Michael J. Rymer, Mark R. Goldman
Uncertainty and risk evaluation during the exploration stage of geothermal development
Quantifying and representing uncertainty for geothermal systems is often ignored, in practice, during the exploration phase of a geothermal development project. We propose that this occurs potentially because the task seems so formidable. The primary goal of this paper is to initiate a dialogue within the geothermal community about: which geothermal uncertainties should receive the most attention
Authors
Jeffrey B. Witter, Whitney J. Trainor-Guitton, Drew L. Siler