Geology, Minerals, Energy, and Geophysics Science Center
Publications
Airborne radiometric maps of Mountain Pass, California
Geophysical investigations of Mountain Pass and vicinity were begun as part of an effort to study regional crustal structures as an aid to understanding the geologic framework and mineral resources of the eastern Mojave Desert. The study area encompasses Mountain Pass, host to one of the world’s largest rare earth element carbonatite deposits. The...
Ponce, David A.; Ponce, David A.; Denton, Kevin M.
Radiocarbon and geologic evidence reveal Ilopango volcano as source of the colossal 'mystery' eruption of 539/40 CE
Ilopango volcano (El Salvador) erupted violently during the Maya Classic Period (250–900 CE) in a densely-populated and intensively-cultivated region of the southern Maya realm, causing regional abandonment of an area covering more than 20,000 km2. However, neither the regional nor global impacts of the Tierra Blanca Joven (TBJ) eruption in...
Dull, Robert A.; Southon, John R.; Kutterolf, Steffen; Anchukaitis, Kevin J.; Freundt, Armin; Wahl, David; Sheets, Payson; Amaroli, Paul; Hernandez, Walter; Weimann, Micheal C.; Oppenheimer, Clive Occurrence and sources of radium in groundwater associated with oil fields in the southern San Joaquin Valley, California
Geochemical data from 40 water wells were used to examine the occurrence and sources of radium (Ra) in groundwater associated with three oil fields in California (Fruitvale, Lost Hills, South Belridge). 226Ra+228Ra activities (range=0.010-0.51 Bq/L) exceeded the 0.185 Bq/L drinking-water standard in 18% of the wells (not drinking-water wells)....
McMahon, Peter B.; Avner Vengosh; Davis, Tracy; Landon, Matthew K.; Rebecca L. Tyne; Wright, Michael; Kulongoski, Justin T.; Hunt, Andrew G.; Peter H. Barry; A.J. Kondash; Z. Wang; Christopher J. Ballentine An initial assessment of areas where landslides could enter the West Arm of Glacier Bay, Alaska and implications for tsunami hazards
Tsunamis generated by landslides in Glacier Bay are uncommon, but have potential to be extraordinarily destructive when they occur. This article identifies areas that are susceptible to landslides that could generate tsunamis and discusses approaches to characterize hazard and risk from these events.
Coe, Jeffrey A.; Schmitt, Robert G.; Bessette-Kirton, Erin Paleoenvironmental, epigraphic, and archaeological evidence of total warfare among the Classic Maya
Despite over a century of archaeological research, the nature and broader consequences of Classic Maya warfare remain poorly understood. Based on frequent epigraphic references and iconographic themes, Classic period (250-950 CE) Maya warfare has largely been viewed as ritualized and limited in scope. Evidence of warfare in the Terminal Classic...
Wahl, David; Phelps, Geoffrey; Estrada-Belli, Francisco; Tokovinine, Alexandre
Geochronologic, isotopic, and geochemical data from igneous rocks in the Lane Mountain area, San Bernardino County, California
We present new geochronologic, isotopic, and geochemical data for selected igneous rocks in the Lane Mountain area, California. We determined SHRIMP-RG U-Pb zircon ages for the following units: (1) Larrea complex (~253 Ma and ~149–146 Ma); (2) Daisy granodiorite (~151 Ma); (3) Jack Spring quartz monzonite (~85–82 Ma); (4) unnamed porphyritic dikes...
Stone, Paul; Brown, Howard J.; Cecil, M. Robinson; Fleck, Robert J.; Vazquez, Jorge A.; Fitzpatrick, John A.; Rosario, Jose J. Crustal architecture beneath the southern Midcontinent (USA) and controls on Mesoproterozoic iron-oxide mineralization from 3D geophysical models
Several types of critical mineral-bearing ore deposits in the southern Midcontinent region of the U.S. are hosted in Mesoproterozoic igneous rocks largely concealed beneath Paleozoic cover. Discerning the architecture of igneous intrusions and volcanic centers in the crust is fundamental to understanding the geologic evolution of this vast region...
McCafferty, Anne E.; Phillips, Jeffrey D.; Hofstra, Albert H.; Day, Warren C.
Extent of the Last Glacial Maximum (Tioga) glaciation in Yosemite National Park and vicinity, California
Yosemite National Park, located in the central Sierra Nevada in California, is an icon of the U.S. National Park system. It is famous for its many spectacular geologic features, which include the towering cliffs and hanging waterfalls of Yosemite Valley and the rounded granite domes, deep blue lakes, and jagged peaks and spires of the high country...
Wahrhaftig, Clyde; Stock, Greg M.; McCracken, Reba G.; Sasnett, Peri; Cyr, Andrew J.
Sand Creek characterization study for Oncorhynchus clarkii virginalis (Rio Grande Cutthroat Trout), Great Sand Dunes National Park and Preserve, Colorado
The Oncorhynchus clarkii virginalis (Rio Grande cutthroat trout, RGCT) has undergone extensive declines in distribution and population. The RGCT is the southernmost distributed subspecies of cutthroat trout. Native to the Rio Grande Basin in Colorado and New Mexico, the subspecies is also found in the headwaters of the Pecos River and Canadian...
Mcgee, Ben N.; Todd, Andrew S.; Kevin K. Terry Hydrocarbons in upland groundwater, Marcellus Shale Region, Northeastern Pennsylvania and Southern New York, USA
Water samples from 50 domestic wells located <1 km (proximal) and >1 km (distal) from shale-gas wells in upland areas of the Marcellus Shale region were analyzed for chemical, isotopic, and groundwater-age tracers. Uplands were targeted because natural mixing with brine and hydrocarbons from deep formations is less common in those areas...
McMahon, Peter B.; Lindsey, Bruce D.; Conlon, Matthew D.; Hunt, Andrew G.; Belitz, Kenneth; Jurgens, Bryant; Varela, Brian Ten-million years of activity within the Eastern California Shear Zone from U-Pb dating of fault-zone opal
Reconstructions of long-term fault activity are essential for understanding both the mechanisms controlling fault behavior and accurate earthquake hazard assessments. Increasing evidence for temporal variations in strain accumulation suggests non-uniform strain rates over a range of historic to geologic timescales. The paucity of long-term records...
Nuriel, Perach; Miller, David M.; Schmidt, Kevin M.; Coble, Matthew A.; Maher, Kate Topographic change detection at Chalk Cliffs, Colorado, USA, using Airborne LiDAR and UAS-based Structure-from-Motion photogrammetry
The Chalk Cliffs debris-flow site is a small headwater catchment incised into highly fractured and hydrothermally altered quartz monzonite in a semi-arid climate. Over half of the extremely steep basin is exposed bedrock. Debris flows occur multiple times per year in response to rainstorm events, typically during the summer monsoon season. The...
Barnhart, Katherine R; Rengers, Francis K.; Ghent Jessica N; Tucker, Gregory E.; Coe, Jeffrey A.; Kean, Jason W.; Smith, Joel B.; Staley, Dennis M.; Kleiber, William; Wiens, Ashton M