Shannon Mahan
My work focuses on the geochronology and associated dosimetry of luminescence dating, with the goal of understanding when, how, and the rates at which mineral grains acquire (and lose!) their luminescence signal.
I graduated from Adams State University (Colorado) with a B.S. in Geology in 1987 and was immediately hired into the USGS in April 1987. For those of you that are counting, this makes me the end of the “baby boomers” and working well into my third decade with the USGS. My career has been as varied as my interests, as I have worked in radiogenic isotopes, hydrology, stable isotopes, gamma spectrometry, and luminescence. I have been the USGS Luminescence Geochronology Lab Director since 1997 and routinely work on 20 to 30 projects during a year throughout the USGS mission areas.
Over the past 40 years, luminescence dating has become a key tool for dating sediments of interest in geologic, paleontologic, and archeologic research and this is my obvious scientific interest. Luminescence is also used to date paleoseismology sites, fluvial terraces (including paleoflood deposits), eolian deposits, and is increasingly used to calibrate wildfire temperatures, sediment transport processes, and thermochronology. The flexibility of luminescence is a key complement to other chronometers such as radiocarbon or cosmogenic nuclides. Like all geochronologic techniques, context is necessary for interpreting and calculating luminescence results and this can be achieved by supplying our lab with associated trench logs, photos, and stratigraphic locations of sample sites if you choose to work with us (Taken from Gray et al, 2015 paper Guide to Luminescence Dating Techniques and their Application for Paleoseismic Research; Mahan and DeWitt, 2019, Principles and history of Luminescence Dating Chapter 1 in Handbook of Luminescence Dating AND Mahan et al, 2022 guide for interpretating and reporting luminescence dating results).
The USGS Luminescence Geochronology Lab is composed of myself, Harrison Gray, and Emma Krolczyk. We are an integral part of multi-disciplinary, multi-agency, and multi-institutional projects that provide chronologic control for Quaternary field studies in the continental United States. The growth of the laboratory is due to the science that our partnership can generate with many other science agencies, both Federal, state, and academic. Additional publications and projects can be viewed from USGS Luminescence Dating Laboratory and on Research Gate.
Professional Experience
2023 - present: Acting Deputy Center Director
2021 - present: TRIGA Reactor System Administrator and Science Advisor
2008 - present: Research Geologist
1987 - 2008: Geologist
Education and Certifications
1986: B.S., Geology, Adams State College
Affiliations and Memberships*
Geological Society of America
Friends of the Pleistocene
INQUA
Science and Products
Filter Total Items: 141
Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States
New and previously published stratigraphic data define Holocene to present sediment storage time scales for Mid-Atlantic river corridors. Empirical distributions of deposit ages and thicknesses were randomly sampled to create synthetic age-depth records. Deposits predating European settlement accumulated at a (median) rate of 0.06 cm yr−1, range from ∼18,000 to 225 yr old, and represent...
Authors
James Pizzuto, Katherine Skalak, Adam Benthem, Shannon A. Mahan, Mahmoud Sherif, Adam Pearson
Luminescence ages and new interpretations of the timing and deposition of Quaternary sediments at Natural Trap Cave, Wyoming Luminescence ages and new interpretations of the timing and deposition of Quaternary sediments at Natural Trap Cave, Wyoming
Natural Trap Cave, located in the Big Horn Mountains of north-central Wyoming, has a history of trapping and preserving a range of North American fauna that plummeted into the deep vertical entrance. These animal remains were buried and preserved within sediments of the main chamber and, in turn, have helped elucidate the procession of faunal dynamics during the latest glacial cycle. The...
Authors
Shannon A. Mahan, John R. Wood, Dave M Lovelace, Juan Laden, Jenny McGuire, Julie Meachen
How similar was the 1983 Mw 6.9 Borah Peak earthquake rupture to its surface-faulting predecessors along the northern Lost River fault zone (Idaho, USA)? How similar was the 1983 Mw 6.9 Borah Peak earthquake rupture to its surface-faulting predecessors along the northern Lost River fault zone (Idaho, USA)?
We excavated trenches at two paleoseismic sites bounding a trans-basin bedrock ridge (the Willow Creek Hills) along the northern Lost River fault zone to explore the uniqueness of the 1983 Mw 6.9 Borah Peak earthquake compared to its prehistoric predecessors. At the Sheep Creek site on the southernmost Warm Springs section, two earthquakes occurred at 9.8−14.0 ka (95% confidence) and 6.5...
Authors
Christopher DuRoss, Richard W. Briggs, Ryan D. Gold, Alexandra Elise Hatem, Austin John Elliott, Jaime Delano, Ivan Medina-Cascales, Harrison J. Gray, Shannon A. Mahan, Sylvia Nicovich, Zachery Lifton, Emily J. Kleber, Greg N. McDonald, Adam Hiscock, Mike Bunds, Nadine G. Reitman
Photomosaics and logs associated with study of West Napa Fault at Ehlers Lane, north of Saint Helena, California Photomosaics and logs associated with study of West Napa Fault at Ehlers Lane, north of Saint Helena, California
The West Napa Fault has previously been mapped as extending ~45 kilometers (km) from northern Vallejo to southern Saint Helena, California, dominantly running along the western edge of Napa Valley. A zone of fault strands (some previously unmapped) along a ~15-km section of the fault ruptured during the 2014 magnitude 6.0 South Napa earthquake, illustrating the need for further...
Authors
Belle E. Philibosian, Robert R. Sickler, Carol S. Prentice, Alexandra J. Pickering, Patrick Gannon, Kiara N. Broudy, Shannon A. Mahan, Jazmine N. Titular, Eli A. Turner, Cameron Folmar, Sierra F. Patterson, Emilie E. Bowman
A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis
A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from evaluation of 554 radiocarbon ages that date earthquake evidence at 14 coastal sites. We...
Authors
Alan Nelson, Christopher DuRoss, Robert C. Witter, Harvey M. Kelsey, Simon E. Engelhart, Shannon A. Mahan, Harrison J. Gray, Andrea D. Hawkes, Benjamin P. Horton, Jason S. Padgett
Synthesis of geochronologic research on Late Pliocene to Holocene emergent shorelines in the lower Savannah River area of southeastern Georgia, USA Synthesis of geochronologic research on Late Pliocene to Holocene emergent shorelines in the lower Savannah River area of southeastern Georgia, USA
Emergent late Pliocene and Pleistocene shoreline deposits, morphologically identifiable Pleistocene shoreline units, and seaward-facing scarps characterize the easternmost Atlantic Coastal Plain (ACP) of the United States of America. In some areas of the ACP, these deposits, units, and scarps have been studied in detail. Within these areas, temporal and spatial data are sufficient for...
Authors
Helaine W. Markewich, Milan J. Pavich, Shannon A. Mahan, Paul R. Bierman, Wilma B. Aleman-Gonzalez, Arthur P. Schultz
River terrace evidence of tectonic processes in the eastern North American plate interior, South Anna River, Virginia River terrace evidence of tectonic processes in the eastern North American plate interior, South Anna River, Virginia
We show that long-recognized seismicity in the central Virginia seismic zone of the eastern North American intraplate setting arises primarily from tectonic processes predicted by new, fully coupled plate tectonic geodynamic models. The study leverages much new geophysical and geologic data following the 2011 Mineral, Virginia, earthquake that ruptured a steeply dipping, northwest...
Authors
Frank J. Pazzaglia, Helen F. Malenda, Matthew L. McGavick, Cody Raup, Mark W. Carter, Claudio Berti, Shannon A. Mahan, Michelle S. Nelson, Tammy M. Rittenour, Ron Counts, Jane K Willenbring, Dru Germanoski, Stephen C. Peters, William D. Holt
Holocene paleoseismology of the Steamboat Mountain Site: Evidence for full‐Llngth rupture of the Teton Fault, Wyoming Holocene paleoseismology of the Steamboat Mountain Site: Evidence for full‐Llngth rupture of the Teton Fault, Wyoming
The 72‐km‐long Teton fault in northwestern Wyoming is an ideal candidate for reconstructing the lateral extent of surface‐rupturing earthquakes and testing models of normal‐fault segmentation. To explore the history of earthquakes on the northern Teton fault, we hand‐excavated two trenches at the Steamboat Mountain site, where the east‐dipping Teton fault has vertically displaced west...
Authors
Christopher DuRoss, Mark S. Zellman, Glenn D. Thackray, Richard W. Briggs, Ryan D. Gold, Shannon A. Mahan
Depth-dependent soil mixing persists across climate zones Depth-dependent soil mixing persists across climate zones
Soil mixing over long (>102 y) timescales enhances nutrient fluxes that support soil ecology, contributes to dispersion of sediment and contaminated material, and modulates fluxes of carbon through Earth’s largest terrestrial carbon reservoir. Despite its foundational importance, we lack robust understanding of the rates and patterns of soil mixing, largely due to a lack of long...
Authors
Harrison J. Gray, Amanda Keen-Zebert, David Furbish, Gregory E. Tucker, Shannon A. Mahan
Neotectonic and paleoseismic analysis of the northwest extent of Holocene surface deformation along the Meers Fault, Oklahoma Neotectonic and paleoseismic analysis of the northwest extent of Holocene surface deformation along the Meers Fault, Oklahoma
TheMeers fault (Oklahoma) is one of fewseismogenic structures with evidence for Holocene surface rupture in the stable continental region of North America. The 37-kilometer-long southeast section of the full 54-kilometer-long Meers fault is interpreted to be Holocene active. The 17-kilometer-long northwest section is considered Quaternary active, but not Holocene active.We reevaluate...
Authors
Kristofer T. Hornsby, Ashley R. Streig, S. Bennett, Jefferson C. Chang, Shannon A. Mahan
Holocene earthquake history and slip rate of the southern Teton fault, Wyoming, USA Holocene earthquake history and slip rate of the southern Teton fault, Wyoming, USA
The 72-km-long Teton normal fault bounds the eastern base of the Teton Range in northwestern Wyoming, USA. Although geomorphic surfaces along the fault record latest Pleistocene to Holocene fault movement, the postglacial earthquake history of the fault has remained enigmatic. We excavated a paleoseismic trench at the Buffalo Bowl site along the southernmost part of the fault to...
Authors
Christopher DuRoss, Ryan D. Gold, Richard W. Briggs, Jaime E. Delano, Dean A. Ostenaa, Mark Zellman, Nicole Cholewinski, Seth Wittke, Shannon A. Mahan
Pleistocene lakes and paleohydrologic environments of the Tecopa basin, California: Constraints on the drainage integration of the Amargosa River Pleistocene lakes and paleohydrologic environments of the Tecopa basin, California: Constraints on the drainage integration of the Amargosa River
The Tecopa basin in eastern California was a terminal basin that episodically held lakes during most of the Quaternary until the basin and its modern stream, the Amargosa River, became tributary to Death Valley. Although long studied for its sedimentology, diagenesis, and paleomagnetism, the basin’s lacustrine and paleoclimate history has not been well understood, and conflicting...
Authors
Marith C. Reheis, John Caskey, Jordon Bright, James B. Paces, Shannon A. Mahan, Elmira Wan
Filter Total Items: 34
Data Release for Luminescence: Tyndall Air Force Base, Panama City, Florida estuarine sediment cores Data Release for Luminescence: Tyndall Air Force Base, Panama City, Florida estuarine sediment cores
As part of the Coastal Sediment Availability and Flux and Defense Advanced Research Protection Agency (DARPA) Reefense projects, scientists from the U.S. Geological Survey (USGS) and St. Petersburg Coastal and Marine Science Center (SPCMSC) conducted a nearshore geophysical survey to map and characterize the stratigraphy of back-barrier bays near Panama City, Florida (FL) in June 2022...
Data Release for Luminescence: OSL Data and Ages in support of the Surficial Geology and Quaternary Fault Map of the Las Vegas Valley, Clark County, Nevada Data Release for Luminescence: OSL Data and Ages in support of the Surficial Geology and Quaternary Fault Map of the Las Vegas Valley, Clark County, Nevada
The data release includes 35 new luminescence ages and 3 new radiocarbon ages. The new age data further brackets the ages of the Las Vegas basin Quaternary stratigraphy and provide new constraints on the timing of Quaternary fault activity.
Geologic Map of the valley corridor of the Niobrara National Scenic River, Nebraska Geologic Map of the valley corridor of the Niobrara National Scenic River, Nebraska
This release of digital geologic map data covers the Niobrara National Scenic River, a 76-mile stretch of river at the northern edge of the Nebraska Sand Hills. The mapped area includes the National Park Service unit of the Niobrara National Scenic River and the adjoining Middle Niobrara Preserve of The Nature Conservancy, and the Fort Niobrara Wildlife Refuge of the U.S. Fish and...
Data Release for Luminescence: Surficial Mapping of the Central Panamint Valley, Inyo County, California Data Release for Luminescence: Surficial Mapping of the Central Panamint Valley, Inyo County, California
Several historic, multi-fault ruptures in the Eastern California Shear Zone (ECSZ) reinforce the need to understand how this rupture style contributes to seismic hazard in complex and diffuse fault zones. Several historic earthquakes in the ECSZ, the 1992 Landers, the 1999 Hector Mine, and the 2019 Ridgecrest rupture sequence, involved complex and multi-fault rupture. However...
Geochronologic and isotopic data for Paleohydrologic history of Pluvial Lake San Agustin, New Mexico Geochronologic and isotopic data for Paleohydrologic history of Pluvial Lake San Agustin, New Mexico
This dataset includes tables of radiocarbon, uranium thorium series, and luminescence geochronologic ages and stable carbon and oxygen isotope compositions for sedimentary and organic samples.
Data Release for Luminescence: Butler Cave, Burnsville Cove, Bath and Highland Counties, VA Data Release for Luminescence: Butler Cave, Burnsville Cove, Bath and Highland Counties, VA
Burnsville Cove in Bath and Highland Counties (Virginia, USA) is a karst region in the Valley and Ridge Province of the Appalachian Mountains. The region contains many caves in Silurian to Devonian limestone, and is well suited for examining geologic controls on cave location and cave passage morphology. In Burnsville Cove, many caves are located preferentially near the axes of synclines...
Data Release for Luminescence: Plio-Pleistocene Hydrology and Marine Isotope Stage (MIS) 4 Deep Springs Lake, Western Great Basin, Inyo County, California Data Release for Luminescence: Plio-Pleistocene Hydrology and Marine Isotope Stage (MIS) 4 Deep Springs Lake, Western Great Basin, Inyo County, California
Deep Springs Valley (DSV) is a hydrologically isolated valley between the White (north and west) and Inyo (south and east) Mountains that is commonly excluded from regional paleohydrologic and paleoclimate studies. Previous studies showed that uplift of Deep Springs ridge (informal name) by the Deep Springs fault defeated streams crossing DSV and hydrologically isolating the valley...
Data Release for Luminescence: Construction and modification of debris-flow alluvial fans as captured in the geomorphic and sedimentary record: examples from the western Sangre de Cristo Mountains, south-central Colorado Data Release for Luminescence: Construction and modification of debris-flow alluvial fans as captured in the geomorphic and sedimentary record: examples from the western Sangre de Cristo Mountains, south-central Colorado
The following report summarizes the dating results from the San Luis Valley-Pioneer Fan 2017-2019 dating project. Within this report, we detail the methodology used by the USGS Luminescence Geochronology Laboratory to obtain ages including sample preparation methods, luminescence measurement, equivalent dose determination, and dating-related calculations. We recommend that this report be...
Data Release for Luminescence: Geologic map of Scoggins Dam, Henry Hagg Lake, and the Scoggins Valley area, Washington County, Oregon Data Release for Luminescence: Geologic map of Scoggins Dam, Henry Hagg Lake, and the Scoggins Valley area, Washington County, Oregon
The Bureau of Reclamation's Scoggins Dam lies within the Gales Creek fault zone southwest of Hillsboro, Oregon. Recent geologic mapping shows the dam to overlie a potentially active strand of the fault. This report describes the geology of the dam in detail and confirms that the dam overlies a strand of the Gales Creek fault. The report documents small faults in the reservoir and off the...
Data Release for Luminescence: Late Holocene rupture history of the Ash Hill Fault, Eastern California Shear Zone, and the potential for seismogenic strain transfer between nearby faults Data Release for Luminescence: Late Holocene rupture history of the Ash Hill Fault, Eastern California Shear Zone, and the potential for seismogenic strain transfer between nearby faults
The following report summarizes the dating results from sedimentary deposits exposed by soil pits in Panamint Valley, CA. Within this report, we detail the methodology used by the USGS Luminescence Geochronology Laboratory to obtain ages including sample preparation methods, luminescence measurement, equivalent dose determination, and dating-related calculations.
Data Release for Luminescence: Paleoseismic liquefaction associated with Holocene earthquakes on the Wallula Fault zone, Southeast Washington, USA Data Release for Luminescence: Paleoseismic liquefaction associated with Holocene earthquakes on the Wallula Fault zone, Southeast Washington, USA
Observations of widespread liquefaction and stratigraphic and structural relationships in a trench across an ambiguous scarp are used to constrain the timing of Holocene earthquakes on the northwest-striking Wallula fault zone in southeast Washington and Oregon. Additional observations and age constraints from OSL analysis of samples collected from large-scale liquefaction features that...
Data Release for Luminescence: Mid to Late Quaternary Geomorphic and Paleoseismic Event History, Cheraw Fault, Colorado Data Release for Luminescence: Mid to Late Quaternary Geomorphic and Paleoseismic Event History, Cheraw Fault, Colorado
Despite its subdued expression and isolated location within the Great Plains of southeastern Colorado, the 80-km-long Cheraw fault may be one of the most active faults in North America east of the Southern Rocky Mountains. We present geomorphic analyses, geochronology, and paleoseismic trenching data to 1) document the rupture history of the ~45-km-long southwestern section of the Cheraw...
Filter Total Items: 15
Science and Products
Filter Total Items: 141
Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States
New and previously published stratigraphic data define Holocene to present sediment storage time scales for Mid-Atlantic river corridors. Empirical distributions of deposit ages and thicknesses were randomly sampled to create synthetic age-depth records. Deposits predating European settlement accumulated at a (median) rate of 0.06 cm yr−1, range from ∼18,000 to 225 yr old, and represent...
Authors
James Pizzuto, Katherine Skalak, Adam Benthem, Shannon A. Mahan, Mahmoud Sherif, Adam Pearson
Luminescence ages and new interpretations of the timing and deposition of Quaternary sediments at Natural Trap Cave, Wyoming Luminescence ages and new interpretations of the timing and deposition of Quaternary sediments at Natural Trap Cave, Wyoming
Natural Trap Cave, located in the Big Horn Mountains of north-central Wyoming, has a history of trapping and preserving a range of North American fauna that plummeted into the deep vertical entrance. These animal remains were buried and preserved within sediments of the main chamber and, in turn, have helped elucidate the procession of faunal dynamics during the latest glacial cycle. The...
Authors
Shannon A. Mahan, John R. Wood, Dave M Lovelace, Juan Laden, Jenny McGuire, Julie Meachen
How similar was the 1983 Mw 6.9 Borah Peak earthquake rupture to its surface-faulting predecessors along the northern Lost River fault zone (Idaho, USA)? How similar was the 1983 Mw 6.9 Borah Peak earthquake rupture to its surface-faulting predecessors along the northern Lost River fault zone (Idaho, USA)?
We excavated trenches at two paleoseismic sites bounding a trans-basin bedrock ridge (the Willow Creek Hills) along the northern Lost River fault zone to explore the uniqueness of the 1983 Mw 6.9 Borah Peak earthquake compared to its prehistoric predecessors. At the Sheep Creek site on the southernmost Warm Springs section, two earthquakes occurred at 9.8−14.0 ka (95% confidence) and 6.5...
Authors
Christopher DuRoss, Richard W. Briggs, Ryan D. Gold, Alexandra Elise Hatem, Austin John Elliott, Jaime Delano, Ivan Medina-Cascales, Harrison J. Gray, Shannon A. Mahan, Sylvia Nicovich, Zachery Lifton, Emily J. Kleber, Greg N. McDonald, Adam Hiscock, Mike Bunds, Nadine G. Reitman
Photomosaics and logs associated with study of West Napa Fault at Ehlers Lane, north of Saint Helena, California Photomosaics and logs associated with study of West Napa Fault at Ehlers Lane, north of Saint Helena, California
The West Napa Fault has previously been mapped as extending ~45 kilometers (km) from northern Vallejo to southern Saint Helena, California, dominantly running along the western edge of Napa Valley. A zone of fault strands (some previously unmapped) along a ~15-km section of the fault ruptured during the 2014 magnitude 6.0 South Napa earthquake, illustrating the need for further...
Authors
Belle E. Philibosian, Robert R. Sickler, Carol S. Prentice, Alexandra J. Pickering, Patrick Gannon, Kiara N. Broudy, Shannon A. Mahan, Jazmine N. Titular, Eli A. Turner, Cameron Folmar, Sierra F. Patterson, Emilie E. Bowman
A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis
A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from evaluation of 554 radiocarbon ages that date earthquake evidence at 14 coastal sites. We...
Authors
Alan Nelson, Christopher DuRoss, Robert C. Witter, Harvey M. Kelsey, Simon E. Engelhart, Shannon A. Mahan, Harrison J. Gray, Andrea D. Hawkes, Benjamin P. Horton, Jason S. Padgett
Synthesis of geochronologic research on Late Pliocene to Holocene emergent shorelines in the lower Savannah River area of southeastern Georgia, USA Synthesis of geochronologic research on Late Pliocene to Holocene emergent shorelines in the lower Savannah River area of southeastern Georgia, USA
Emergent late Pliocene and Pleistocene shoreline deposits, morphologically identifiable Pleistocene shoreline units, and seaward-facing scarps characterize the easternmost Atlantic Coastal Plain (ACP) of the United States of America. In some areas of the ACP, these deposits, units, and scarps have been studied in detail. Within these areas, temporal and spatial data are sufficient for...
Authors
Helaine W. Markewich, Milan J. Pavich, Shannon A. Mahan, Paul R. Bierman, Wilma B. Aleman-Gonzalez, Arthur P. Schultz
River terrace evidence of tectonic processes in the eastern North American plate interior, South Anna River, Virginia River terrace evidence of tectonic processes in the eastern North American plate interior, South Anna River, Virginia
We show that long-recognized seismicity in the central Virginia seismic zone of the eastern North American intraplate setting arises primarily from tectonic processes predicted by new, fully coupled plate tectonic geodynamic models. The study leverages much new geophysical and geologic data following the 2011 Mineral, Virginia, earthquake that ruptured a steeply dipping, northwest...
Authors
Frank J. Pazzaglia, Helen F. Malenda, Matthew L. McGavick, Cody Raup, Mark W. Carter, Claudio Berti, Shannon A. Mahan, Michelle S. Nelson, Tammy M. Rittenour, Ron Counts, Jane K Willenbring, Dru Germanoski, Stephen C. Peters, William D. Holt
Holocene paleoseismology of the Steamboat Mountain Site: Evidence for full‐Llngth rupture of the Teton Fault, Wyoming Holocene paleoseismology of the Steamboat Mountain Site: Evidence for full‐Llngth rupture of the Teton Fault, Wyoming
The 72‐km‐long Teton fault in northwestern Wyoming is an ideal candidate for reconstructing the lateral extent of surface‐rupturing earthquakes and testing models of normal‐fault segmentation. To explore the history of earthquakes on the northern Teton fault, we hand‐excavated two trenches at the Steamboat Mountain site, where the east‐dipping Teton fault has vertically displaced west...
Authors
Christopher DuRoss, Mark S. Zellman, Glenn D. Thackray, Richard W. Briggs, Ryan D. Gold, Shannon A. Mahan
Depth-dependent soil mixing persists across climate zones Depth-dependent soil mixing persists across climate zones
Soil mixing over long (>102 y) timescales enhances nutrient fluxes that support soil ecology, contributes to dispersion of sediment and contaminated material, and modulates fluxes of carbon through Earth’s largest terrestrial carbon reservoir. Despite its foundational importance, we lack robust understanding of the rates and patterns of soil mixing, largely due to a lack of long...
Authors
Harrison J. Gray, Amanda Keen-Zebert, David Furbish, Gregory E. Tucker, Shannon A. Mahan
Neotectonic and paleoseismic analysis of the northwest extent of Holocene surface deformation along the Meers Fault, Oklahoma Neotectonic and paleoseismic analysis of the northwest extent of Holocene surface deformation along the Meers Fault, Oklahoma
TheMeers fault (Oklahoma) is one of fewseismogenic structures with evidence for Holocene surface rupture in the stable continental region of North America. The 37-kilometer-long southeast section of the full 54-kilometer-long Meers fault is interpreted to be Holocene active. The 17-kilometer-long northwest section is considered Quaternary active, but not Holocene active.We reevaluate...
Authors
Kristofer T. Hornsby, Ashley R. Streig, S. Bennett, Jefferson C. Chang, Shannon A. Mahan
Holocene earthquake history and slip rate of the southern Teton fault, Wyoming, USA Holocene earthquake history and slip rate of the southern Teton fault, Wyoming, USA
The 72-km-long Teton normal fault bounds the eastern base of the Teton Range in northwestern Wyoming, USA. Although geomorphic surfaces along the fault record latest Pleistocene to Holocene fault movement, the postglacial earthquake history of the fault has remained enigmatic. We excavated a paleoseismic trench at the Buffalo Bowl site along the southernmost part of the fault to...
Authors
Christopher DuRoss, Ryan D. Gold, Richard W. Briggs, Jaime E. Delano, Dean A. Ostenaa, Mark Zellman, Nicole Cholewinski, Seth Wittke, Shannon A. Mahan
Pleistocene lakes and paleohydrologic environments of the Tecopa basin, California: Constraints on the drainage integration of the Amargosa River Pleistocene lakes and paleohydrologic environments of the Tecopa basin, California: Constraints on the drainage integration of the Amargosa River
The Tecopa basin in eastern California was a terminal basin that episodically held lakes during most of the Quaternary until the basin and its modern stream, the Amargosa River, became tributary to Death Valley. Although long studied for its sedimentology, diagenesis, and paleomagnetism, the basin’s lacustrine and paleoclimate history has not been well understood, and conflicting...
Authors
Marith C. Reheis, John Caskey, Jordon Bright, James B. Paces, Shannon A. Mahan, Elmira Wan
Filter Total Items: 34
Data Release for Luminescence: Tyndall Air Force Base, Panama City, Florida estuarine sediment cores Data Release for Luminescence: Tyndall Air Force Base, Panama City, Florida estuarine sediment cores
As part of the Coastal Sediment Availability and Flux and Defense Advanced Research Protection Agency (DARPA) Reefense projects, scientists from the U.S. Geological Survey (USGS) and St. Petersburg Coastal and Marine Science Center (SPCMSC) conducted a nearshore geophysical survey to map and characterize the stratigraphy of back-barrier bays near Panama City, Florida (FL) in June 2022...
Data Release for Luminescence: OSL Data and Ages in support of the Surficial Geology and Quaternary Fault Map of the Las Vegas Valley, Clark County, Nevada Data Release for Luminescence: OSL Data and Ages in support of the Surficial Geology and Quaternary Fault Map of the Las Vegas Valley, Clark County, Nevada
The data release includes 35 new luminescence ages and 3 new radiocarbon ages. The new age data further brackets the ages of the Las Vegas basin Quaternary stratigraphy and provide new constraints on the timing of Quaternary fault activity.
Geologic Map of the valley corridor of the Niobrara National Scenic River, Nebraska Geologic Map of the valley corridor of the Niobrara National Scenic River, Nebraska
This release of digital geologic map data covers the Niobrara National Scenic River, a 76-mile stretch of river at the northern edge of the Nebraska Sand Hills. The mapped area includes the National Park Service unit of the Niobrara National Scenic River and the adjoining Middle Niobrara Preserve of The Nature Conservancy, and the Fort Niobrara Wildlife Refuge of the U.S. Fish and...
Data Release for Luminescence: Surficial Mapping of the Central Panamint Valley, Inyo County, California Data Release for Luminescence: Surficial Mapping of the Central Panamint Valley, Inyo County, California
Several historic, multi-fault ruptures in the Eastern California Shear Zone (ECSZ) reinforce the need to understand how this rupture style contributes to seismic hazard in complex and diffuse fault zones. Several historic earthquakes in the ECSZ, the 1992 Landers, the 1999 Hector Mine, and the 2019 Ridgecrest rupture sequence, involved complex and multi-fault rupture. However...
Geochronologic and isotopic data for Paleohydrologic history of Pluvial Lake San Agustin, New Mexico Geochronologic and isotopic data for Paleohydrologic history of Pluvial Lake San Agustin, New Mexico
This dataset includes tables of radiocarbon, uranium thorium series, and luminescence geochronologic ages and stable carbon and oxygen isotope compositions for sedimentary and organic samples.
Data Release for Luminescence: Butler Cave, Burnsville Cove, Bath and Highland Counties, VA Data Release for Luminescence: Butler Cave, Burnsville Cove, Bath and Highland Counties, VA
Burnsville Cove in Bath and Highland Counties (Virginia, USA) is a karst region in the Valley and Ridge Province of the Appalachian Mountains. The region contains many caves in Silurian to Devonian limestone, and is well suited for examining geologic controls on cave location and cave passage morphology. In Burnsville Cove, many caves are located preferentially near the axes of synclines...
Data Release for Luminescence: Plio-Pleistocene Hydrology and Marine Isotope Stage (MIS) 4 Deep Springs Lake, Western Great Basin, Inyo County, California Data Release for Luminescence: Plio-Pleistocene Hydrology and Marine Isotope Stage (MIS) 4 Deep Springs Lake, Western Great Basin, Inyo County, California
Deep Springs Valley (DSV) is a hydrologically isolated valley between the White (north and west) and Inyo (south and east) Mountains that is commonly excluded from regional paleohydrologic and paleoclimate studies. Previous studies showed that uplift of Deep Springs ridge (informal name) by the Deep Springs fault defeated streams crossing DSV and hydrologically isolating the valley...
Data Release for Luminescence: Construction and modification of debris-flow alluvial fans as captured in the geomorphic and sedimentary record: examples from the western Sangre de Cristo Mountains, south-central Colorado Data Release for Luminescence: Construction and modification of debris-flow alluvial fans as captured in the geomorphic and sedimentary record: examples from the western Sangre de Cristo Mountains, south-central Colorado
The following report summarizes the dating results from the San Luis Valley-Pioneer Fan 2017-2019 dating project. Within this report, we detail the methodology used by the USGS Luminescence Geochronology Laboratory to obtain ages including sample preparation methods, luminescence measurement, equivalent dose determination, and dating-related calculations. We recommend that this report be...
Data Release for Luminescence: Geologic map of Scoggins Dam, Henry Hagg Lake, and the Scoggins Valley area, Washington County, Oregon Data Release for Luminescence: Geologic map of Scoggins Dam, Henry Hagg Lake, and the Scoggins Valley area, Washington County, Oregon
The Bureau of Reclamation's Scoggins Dam lies within the Gales Creek fault zone southwest of Hillsboro, Oregon. Recent geologic mapping shows the dam to overlie a potentially active strand of the fault. This report describes the geology of the dam in detail and confirms that the dam overlies a strand of the Gales Creek fault. The report documents small faults in the reservoir and off the...
Data Release for Luminescence: Late Holocene rupture history of the Ash Hill Fault, Eastern California Shear Zone, and the potential for seismogenic strain transfer between nearby faults Data Release for Luminescence: Late Holocene rupture history of the Ash Hill Fault, Eastern California Shear Zone, and the potential for seismogenic strain transfer between nearby faults
The following report summarizes the dating results from sedimentary deposits exposed by soil pits in Panamint Valley, CA. Within this report, we detail the methodology used by the USGS Luminescence Geochronology Laboratory to obtain ages including sample preparation methods, luminescence measurement, equivalent dose determination, and dating-related calculations.
Data Release for Luminescence: Paleoseismic liquefaction associated with Holocene earthquakes on the Wallula Fault zone, Southeast Washington, USA Data Release for Luminescence: Paleoseismic liquefaction associated with Holocene earthquakes on the Wallula Fault zone, Southeast Washington, USA
Observations of widespread liquefaction and stratigraphic and structural relationships in a trench across an ambiguous scarp are used to constrain the timing of Holocene earthquakes on the northwest-striking Wallula fault zone in southeast Washington and Oregon. Additional observations and age constraints from OSL analysis of samples collected from large-scale liquefaction features that...
Data Release for Luminescence: Mid to Late Quaternary Geomorphic and Paleoseismic Event History, Cheraw Fault, Colorado Data Release for Luminescence: Mid to Late Quaternary Geomorphic and Paleoseismic Event History, Cheraw Fault, Colorado
Despite its subdued expression and isolated location within the Great Plains of southeastern Colorado, the 80-km-long Cheraw fault may be one of the most active faults in North America east of the Southern Rocky Mountains. We present geomorphic analyses, geochronology, and paleoseismic trenching data to 1) document the rupture history of the ~45-km-long southwestern section of the Cheraw...
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