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
Earthquake Geology and Paleoseismology Overview
San Andreas Fault System in Southern California
Pacific Northwest Geologic Mapping: Northern Pacific Border, Cascades and Columbia
Task 1-Grand Traverse Bay Quaternary Geologic Mapping
How Big and How Frequent Are Earthquakes on the Wasatch Fault?
Datasets documenting neotectonic mapping of Puerto Rico
Digital data for the geologic map of Scoggins Dam, Henry Hagg Lake, and Scoggins Valley, Washington County, Oregon
Data Release for Luminescence: Tyndall Air Force Base, Panama City, Florida estuarine sediment cores
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
Geologic Map of the valley corridor of the Niobrara National Scenic River, Nebraska
Data Release for Luminescence: Surficial Mapping of the Central Panamint Valley, Inyo County, California
Geochronologic and isotopic data for Paleohydrologic history of Pluvial Lake San Agustin, New Mexico
Data Release for Luminescence: Butler Cave, Burnsville Cove, Bath and Highland Counties, VA
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: 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: Geologic map of Scoggins Dam, Henry Hagg Lake, and the Scoggins Valley area, Washington County, Oregon
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
Surficial geology and Quaternary fault map of the Las Vegas Valley, Clark County, Nevada
Logs and scarp data from a paleoseismic investigation of the Surprise Valley fault zone, Modoc County, California
Paleoseismology of the Nephi Segment of the Wasatch Fault Zone, Juab County, Utah - Preliminary Results From Two Large Exploratory Trenches at Willow Creek
In 2004, we identified a small parcel of U.S. Forest Service land at the mouth of Willow Creek (about 5 km west of Mona, Utah) that was suitable for trenching. At the Willow Creek site, which is near the middle of the southern strand of the Nephi segment, the WFZ has vertically displaced alluvial-fan deposits >6-7 m, forming large, steep, multiple-event scarps. In May 2005, we dug two 4- to 5-m-de
Trench Logs and Scarp Data from an Investigation of the Steens Fault Zone, Bog Hot Valley and Pueblo Valley, Humboldt County, Nevada
Data Related to Late Quaternary Surface Faulting on the Sangre de Cristo Fault, Rito Seco Site, Costilla County, Colorado
Geologic and geophysical maps of the Las Vegas 30' x 60' quadrangle, Clark and Nye counties, Nevada, and Inyo County, California
Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California
Log and data from a trench across the Hubbell Spring Fault Zone, Bernalillo County, New Mexico
High-resolution geophysical and geochronological analysis of a relict shoreface deposit offshore central California: Implications for slip rate along the Hosgri fault
Reconstructing the geomorphic evolution and sediment budget history of a dynamic barrier island: Anclote Key, Florida
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
Pliocene–Pleistocene hydrology and pluvial lake during Marine Isotope Stages 5a and 4, Deep Springs Valley, western Great Basin, Inyo County, California
Paleohydrologic history of pluvial lake San Agustin, New Mexico: Tracking changing effective moisture in southwest North America through the last glacial transition
Reconstructing the geomorphic evolution and sediment budget history of a dynamic barrier island: Anclote Key, Florida
Decadal to centennial variations in sediment availability are a primary driver of coastal change within barrier systems. Models help explore how barrier morphology relates to past changes in magnitude of sediment availability, but this requires insights and validation from field efforts. In this study, we investigate the progradation of Anclote Key via its morphostratigraphy, a presently dynamic b
Guide for interpreting and reporting luminescence dating results
Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States
Luminescence ages and new interpretations of the timing and deposition of Quaternary sediments at Natural Trap Cave, Wyoming
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)?
Photomosaics and logs associated with study of West Napa Fault at Ehlers Lane, north of Saint Helena, California
A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis
Science and Products
Earthquake Geology and Paleoseismology Overview
San Andreas Fault System in Southern California
Pacific Northwest Geologic Mapping: Northern Pacific Border, Cascades and Columbia
Task 1-Grand Traverse Bay Quaternary Geologic Mapping
How Big and How Frequent Are Earthquakes on the Wasatch Fault?
Datasets documenting neotectonic mapping of Puerto Rico
Digital data for the geologic map of Scoggins Dam, Henry Hagg Lake, and Scoggins Valley, Washington County, Oregon
Data Release for Luminescence: Tyndall Air Force Base, Panama City, Florida estuarine sediment cores
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
Geologic Map of the valley corridor of the Niobrara National Scenic River, Nebraska
Data Release for Luminescence: Surficial Mapping of the Central Panamint Valley, Inyo County, California
Geochronologic and isotopic data for Paleohydrologic history of Pluvial Lake San Agustin, New Mexico
Data Release for Luminescence: Butler Cave, Burnsville Cove, Bath and Highland Counties, VA
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: 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: Geologic map of Scoggins Dam, Henry Hagg Lake, and the Scoggins Valley area, Washington County, Oregon
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
Surficial geology and Quaternary fault map of the Las Vegas Valley, Clark County, Nevada
Logs and scarp data from a paleoseismic investigation of the Surprise Valley fault zone, Modoc County, California
Paleoseismology of the Nephi Segment of the Wasatch Fault Zone, Juab County, Utah - Preliminary Results From Two Large Exploratory Trenches at Willow Creek
In 2004, we identified a small parcel of U.S. Forest Service land at the mouth of Willow Creek (about 5 km west of Mona, Utah) that was suitable for trenching. At the Willow Creek site, which is near the middle of the southern strand of the Nephi segment, the WFZ has vertically displaced alluvial-fan deposits >6-7 m, forming large, steep, multiple-event scarps. In May 2005, we dug two 4- to 5-m-de
Trench Logs and Scarp Data from an Investigation of the Steens Fault Zone, Bog Hot Valley and Pueblo Valley, Humboldt County, Nevada
Data Related to Late Quaternary Surface Faulting on the Sangre de Cristo Fault, Rito Seco Site, Costilla County, Colorado
Geologic and geophysical maps of the Las Vegas 30' x 60' quadrangle, Clark and Nye counties, Nevada, and Inyo County, California
Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California
Log and data from a trench across the Hubbell Spring Fault Zone, Bernalillo County, New Mexico
High-resolution geophysical and geochronological analysis of a relict shoreface deposit offshore central California: Implications for slip rate along the Hosgri fault
Reconstructing the geomorphic evolution and sediment budget history of a dynamic barrier island: Anclote Key, Florida
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
Pliocene–Pleistocene hydrology and pluvial lake during Marine Isotope Stages 5a and 4, Deep Springs Valley, western Great Basin, Inyo County, California
Paleohydrologic history of pluvial lake San Agustin, New Mexico: Tracking changing effective moisture in southwest North America through the last glacial transition
Reconstructing the geomorphic evolution and sediment budget history of a dynamic barrier island: Anclote Key, Florida
Decadal to centennial variations in sediment availability are a primary driver of coastal change within barrier systems. Models help explore how barrier morphology relates to past changes in magnitude of sediment availability, but this requires insights and validation from field efforts. In this study, we investigate the progradation of Anclote Key via its morphostratigraphy, a presently dynamic b
Guide for interpreting and reporting luminescence dating results
Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States
Luminescence ages and new interpretations of the timing and deposition of Quaternary sediments at Natural Trap Cave, Wyoming
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)?
Photomosaics and logs associated with study of West Napa Fault at Ehlers Lane, north of Saint Helena, California
A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government