Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2403
Layered intrusions in the Precambrian: Observations and perspectives
Layered intrusions are plutonic bodies of cumulates that form by the crystallization of mantle-derived melts. These intrusions are characterized by igneous layering distinguishable by shifts in mineralogy, texture, or composition. Layered intrusions have been fundamental to our understanding of igneous petrology; however, it is their status as important repositories of critical metals – such as pl
Authors
William D. Smith, Michael Jenkins, Claudia T. Augustin, Ville J. Virtanen, Zoja Vukmanovic, Brian O'Driscoll
Twentieth century extreme precipitation detected in a high-resolution, coastal lake-sediment record from California
California faces increasing economic and societal risks from extreme precipitation and flooding associated with atmospheric rivers (ARs) under projected twenty-first century climate warming. Lake sediments can retain signals of past extreme precipitation events, allowing reconstructions beyond the period of instrumental records. Here, we calibrate AR-related extreme precipitation from the last cen
Authors
Clarke Alexandra Knight, David Wahl, Jason A. Addison, Mark Baskaran, R. Scott Anderson, Marie Rhondelle Champagne, Lysanna Anderson, Liubov S. Presnetsova, Beth Elaine Caissie, Scott W. Starratt
The geometry of fault reactivation and uplift along the central part of the Maacama fault zone, northern California Coast Ranges (USA)
Fault reactivation of bedrock structures in active fault zones influences stress state and earthquake rupture phenomena through the introduction of weak slip surfaces that impact fault zone geometry and width. Yet, geometric relationships between modern faults and older reactivated faults are difficult to quantify in rocks that have experienced multiple deformation episodes. We used new geologic m
Authors
Benjamin Melosh, Robert J. McLaughlin, Henry Ohlin
New U-Pb geochronology and geochemistry of Paleozoic metaigneous rocks from western Yukon and eastern Alaska, cross-border synthesis, and implications for tectonic models
The tectonic evolution of and relation between the Yukon-Tanana terrane and the Lake George assemblage, as well as other associated tectonic assemblages in western Yukon and eastern Alaska, have been debated for decades. The Yukon-Tanana terrane is widely considered to be an allochthonous rifted fragment derived from the Laurentian continental margin, whereas the Lake George assemblage and associa
Authors
Cynthia Dusel-Bacon, James K. Mortensen
Field evidence and indicators of rockfall fragmentation and implications for mobility
Rockfall fragmentation can play an important role in hazard studies and the design of protective measures. However, the current lack of modeling tools that incorporate rock fragmentation mechanics is a limitation to enhancing studies and design. This research investigates the fragmentation patterns of rockfalls and analyzes the resulting distribution of fragment sizes within corresponding rockfall
Authors
Camilla Lanfranconi, Paolo Frattini, Federico Agliardi, Greg M. Stock, Brian D. Collins, Giovanni Crosta
Bayesian approaches to proxy uncertainty quantification in paleoecology: A mathematical justification and practical integration
Paleoenvironmental data are essential for reconstructing environmental conditions in the distant past, and these reconstructions strongly depend on proxies and age–depth models. Proxies are indirect measurements that substitute for variables that cannot be directly measured, such as past precipitation. Conversely, an age–depth model is a tool that correlates the observed proxy with a specific mome
Authors
Marco A. Aquino-Lopez, Lysanna Anderson, Joan-Albert Sanchez-Cabeza, Ana Carolina Ruiz-Fernandez, J. Andrés Christen
Subduction zone geometry modulates the megathrust earthquake cycle: Magnitude, recurrence, and variability
Megathrust geometric properties exhibit some of the strongest correlations with maximum earthquake magnitude in global surveys of large subduction zone earthquakes, but the mechanisms through which fault geometry influences subduction earthquake cycle dynamics remain unresolved. Here, we develop 39 models of sequences of earthquakes and aseismic slip (SEAS) on variably-dipping planar and variably-
Authors
James Burkhardt Biemiller, Alice-Agnes Gabriel, Dave May, Lydia M. Staisch
Assessing potential effects of oil and gas development activities on groundwater quality near and overlying the Elk Hills and North Coles Levee Oil Fields, San Joaquin Valley, California
Groundwater resources are utilized near areas of intensive oil and gas development in California’s San Joaquin Valley. In this study, we examined chemical and isotopic data to assess if thermogenic gas or saline water from oil producing formations have mixed with groundwater near the Elk Hills and North Coles Levee Oil Fields in the southwestern San Joaquin Valley. Major ion concentrations and sta
Authors
John G. Warden, Matthew K. Landon, Michael J. Stephens, Tracy Davis, Janice M. Gillespie, Peter B. McMahon, Justin T. Kulongoski, Andrew G. Hunt, David H. Shimabukuro, Riley Gannon, Lyndsay B. Ball
Geochemistry of Archean komatiitic greenstone terranes of the Wyoming Province: Implications for geodynamic setting and mineralization
No abstract available.
Authors
Lisa Joanne Zieman, Jacob Evan Poletti, Michael Jenkins
A multi-methodological approach: Combining textural observations and geochronology to study the J-M Reef Package and its Hanging Wall, Stillwater Complex, Montana
No abstract available.
Authors
Michael Jenkins, Sam R. Corson, Ennis Geraghty, S.L. Kamo, Heather A. Lowers, James E. Mungall
A Bayesian age from dispersed plagioclase and zircon dates in the Los Chocoyos ash, Central America
The eruption that produced the modern Atitlán caldera in Guatemala has a Volcanic Explosivity Index (VEI) greater than 8, making it the largest of the Quaternary in the Central American Volcanic Arc (CAVA). It generated ∼1220 km3 (730 km3 dense rock equivalent) of dispersed rhyolitic ash and unwelded pyroclastic flow deposits known as the Los Chocoyos ash. Despite its scale, the age of the Los Cho
Authors
Alec Baudry, Bradley S. Singer, Brian Jicha, Christine E. Jilly-Rehak, Jorge A. Vazquez, C. Brenhin Keller
Controls on stable methane isotope signatures in northern peatlands and potential shifts in signatures under permafrost thaw scenarios
Northern peatlands are a globally significant source of methane (CH4), and emissions are projected to increase due to warming and permafrost loss. Understanding the microbial mechanisms behind patterns in CH4 production in these systems will be key to predicting annual emissions changes, with stable carbon isotopes (δ13C-CH4) being a powerful tool for characterizing these drivers. Given that δ13C
Authors
McKenzie A. Kuhn, Ruth K. Varner, Carmody K. McCalley, Clarice R. Perryman, Mika Aurela, Sophia A. Burke, Jeffrey Chanton, Patrick Crill, Jessica DelGreco, Jia Deng, Liam Heffernan, Christina Herrick, Suzanne B. Hodgkins, Cheristy P. Jones, Sari Juutinen, Evan S. Kane, Louis J. Lamit, Tuula Larmola, Erik Lilleskov, David Olefeldt, Michael W. Palace, Virginia I. Rich, Christopher Schulze, Joanne H. Shorter, Franklin Sullivan, Oliver Sonnentag, Merritt R. Turetsky, Mark Waldrop