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
Paleoseismology of the Southern Section of the Black Mountains and Southern Death Valley Fault Zones, Death Valley, United States
A geochronologic framework for the Ziegler Reservoir fossil site, Snowmass Village, Colorado
The notion of climate-driven strath-terrace production assessed via dissimilar stream-process response to late Quaternary climate
Stream capture to form Red Pass, northern Soda Mountains, California
Holocene and latest Pleistocene paleoseismology of the Salt Lake City segment of the Wasatch Fault Zone, Utah, at the Penrose Drive Trench Site
Late quaternary paleoseismology of the west valley fault zone: Insights from the Baileys Lake trench site
History of late Holocene earthquakes at the Willow Creek site on the Nephi segment, Wasatch fault zone, Utah
Latest Quaternary paleoseismology and evidence of distributed dextral shear along the Mohawk Valley fault zone, northern Walker Lane, California
Geochronology and paleoenvironment of pluvial Harper Lake, Mojave Desert, California, USA
A non-destructive method for dating human remains
Constraints on the age of the Great Sand Dunes, Colorado, from subsurface stratigraphy and OSL dates
Late Quaternary stream piracy and strath terrace formation along the Belle Fourche and lower Cheyenne Rivers, South Dakota and Wyoming
Science and Products
- Science
- Data
Filter Total Items: 20No Result Found
- Maps
Filter Total Items: 13
- Publications
Filter Total Items: 136
Paleoseismology of the Southern Section of the Black Mountains and Southern Death Valley Fault Zones, Death Valley, United States
The Death Valley Fault System (DVFS) is part of the southern Walker Lane–eastern California shear zone. The normal Black Mountains Fault Zone (BMFZ) and the right-lateral Southern Death Valley Fault Zone (SDVFZ) are two components of the DVFS. Estimates of late Pleistocene-Holocene slip rates and recurrence intervals for these two fault zones are uncertain owing to poor relative age control. The BAuthorsMarsha S. Sohn, Jeffrey R. Knott, Shannon MahanA geochronologic framework for the Ziegler Reservoir fossil site, Snowmass Village, Colorado
The Ziegler Reservoir fossil site near Snowmass Village, Colorado, provides a unique opportunity to reconstruct high-altitude paleoenvironmental conditions in the Rocky Mountains during the last interglacial period. We used four different techniques to establish a chronological framework for the site. Radiocarbon dating of lake organics, bone collagen, and shell carbonate, and in situ cosmogenic 1AuthorsShannon Mahan, Harrison J. Gray, Jeffrey S. Pigati, Jim Wilson, Nathaniel A. Lifton, James B. Paces, Maarten BlaauwThe notion of climate-driven strath-terrace production assessed via dissimilar stream-process response to late Quaternary climate
Previous research results from the Gabilan Mesa are combined with new optically stimulated luminescence (OSL) age estimates and sedimentological analyses with the aim of identifying factors that inhibit climate-driven strath-terrace production, and factors that make possible strath-terrace production independent of climate forcing. The factors are revealed by comparing the morphostratigraphy and OAuthorsAntonio F. García, Shannon MahanStream capture to form Red Pass, northern Soda Mountains, California
Red Pass, a narrow cut through the Soda Mountains important for prehistoric and early historic travelers, is quite young geologically. Its history of downcutting to capture streams west of the Soda Mountains, thereby draining much of eastern Fort Irwin, is told by the contrast in alluvial fan sediments on either side of the pass. Old alluvial fan deposits (>500 ka) were shed westward off an intacAuthorsDavid M. Miller, Shannon A. MahanHolocene and latest Pleistocene paleoseismology of the Salt Lake City segment of the Wasatch Fault Zone, Utah, at the Penrose Drive Trench Site
The Salt Lake City segment (SLCS) of the Wasatch fault zone (WFZ) and the West Valley fault zone (WVFZ) compromise Holocene-active normal faults that bound a large intrabasin graben in northern Salt Lake Valley and have evidence of recurrent, large-magnitude (M ~6-7) surface-faulting earthquakes. However, at the time of this investigation, questions remained regarding the timing, displacement, andAuthorsChristopher B. DuRoss, Michael D. Hylland, Greg N. McDonald, Anthony J. Crone, Stephen F. Personius, Ryan D. Gold, Shannon MahanLate quaternary paleoseismology of the west valley fault zone: Insights from the Baileys Lake trench site
No abstract available.AuthorsMichael D. Hylland, Christopher B. DuRoss, Greg N. McDonald, Susan S. Olig, Charles G. Oviatt, Shannon Mahan, Anthony J. Crone, Stephen F. PersoniusHistory of late Holocene earthquakes at the Willow Creek site on the Nephi segment, Wasatch fault zone, Utah
This 43-page report presents new data from the Willow Creek site that provides well-defined and narrow bounds on the times of the three youngest earthquakes on the southern strand of the Nephi segment, Wasatch Fault zone, and refines the time of the youngest earthquake to about 200 years ago. This is the youngest surface rupture on the entire Wasatch fault zone, which occurred about a century or lAuthorsAnthony J. Crone, Stephen F. Personius, Christopher DuRoss, Michael N. Machette, Shannon A. MahanLatest Quaternary paleoseismology and evidence of distributed dextral shear along the Mohawk Valley fault zone, northern Walker Lane, California
The dextral-slip Mohawk Valley fault zone (MVFZ) strikes northwestward along the eastern margin of the Sierra Nevada in the northern Walker Lane. Geodetic block modeling indicates that the MVFZ may accommodate ~3 mm/yr of regional dextral strain, implying that it is the highest slip-rate strike-slip fault in the region; however, only limited geologic data are available to constrain the system’s slAuthorsRyan D. Gold, Richard W. Briggs, Stephen Personius, Anthony J. Crone, Shannon A. Mahan, Stephen AngsterGeochronology and paleoenvironment of pluvial Harper Lake, Mojave Desert, California, USA
Accurate reconstruction of the paleo-Mojave River and pluvial lake (Harper, Manix, Cronese, and Mojave) system of southern California is critical to understanding paleoclimate and the North American polar jet stream position over the last 500 ka. Previous studies inferred a polar jet stream south of 35°N at 18 ka and at ~ 40°N at 17–14 ka. Highstand sediments of Harper Lake, the upstream-most pluvAuthorsAnna L. Garcia, Jeffrey R. Knott, Shannon Mahan, Jordan BrightA non-destructive method for dating human remains
The skeletal remains of several Native Americans were recovered in an eroded state from a creek bank in northeastern New Mexico. Subsequently stored in a nearby museum, the remains became lost for almost 36 years. In a recent effort to repatriate the remains, it was necessary to fit them into a cultural chronology in order to determine the appropriate tribe(s) for consultation pursuant to the NatiAuthorsWarren K. Lail, David Sammeth, Shannon Mahan, Jason NevinsConstraints on the age of the Great Sand Dunes, Colorado, from subsurface stratigraphy and OSL dates
The age of the Great Sand Dunes has been debated for nearly 150 yr. Seven ages ranging from Miocene to late Holocene have been proposed for them. This paper presents new information—chiefly subsurface stratigraphic data, OSL dates, and geomorphic evidence—that indicates that the Great Sand Dunes began to form in the latter part of the middle Pleistocene. The dunes overlie a thick wedge of piedmontAuthorsRichard F. Madole, Shannon Mahan, Joseph H. Romig, Jeremy C. HavensLate Quaternary stream piracy and strath terrace formation along the Belle Fourche and lower Cheyenne Rivers, South Dakota and Wyoming
Stream piracy substantially affected the geomorphic evolution of the Missouri River watershed and drainages within, including the Little Missouri, Cheyenne, Belle Fourche, Bad, and White Rivers. The ancestral Cheyenne River eroded headward in an annular pattern around the eastern and southern Black Hills and pirated the headwaters of the ancestral Bad and White Rivers after ~ 660 ka. The headwaterAuthorsJohn F. Stamm, Robert R. Hendricks, J. Foster Sawyer, Shannon Mahan, Brent J. Zaprowski, Nicholas M. Geibel, David C. Azzolini
*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