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
High resolution shallow geologic characterization of a late Pleistocene eolian environment using ground penetrating radar and optically stimulated luminescence techniques: North Carolina, USA
Late pleistocene aggradation and degradation of the lower colorado river: Perspectives from the Cottonwood area and other reconnaissance below Boulder Canyon
Optically stimulated luminescence age controls on late Pleistocene and Holocene coastal lithosomes, North Carolina, USA
A 3-Dimensional Model of Water-Bearing Sequences in the Dominguez Gap Region, Long Beach, California
Late quaternary paleoseismology of the southern Steens fault zone, northern Nevada
Paleoecology reconstruction from trapped gases in a fulgurite from the late Pleistocene of the Libyan Desert
An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils
Late Quaternary stratigraphy and luminescence geochronology of the northeastern Mojave Desert
Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front
Numerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-se
Ages of Quaternary Rio Grande terrace-fill deposits, Albuquerque area, New Mexico
Development of spatially diverse and complex dune-field patterns: Gran Desierto Dune Field, Sonora, Mexico
Science and Products
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High resolution shallow geologic characterization of a late Pleistocene eolian environment using ground penetrating radar and optically stimulated luminescence techniques: North Carolina, USA
Geophysical surveys, sedimentology, and optically-stimulated luminescence age analyses were used to assess the geologic development of a coastal system near Swansboro, NC. This area is a significant Woodland Period Native American habitation and is designated the "Broad Reach" archaeological site. 2-d and 3-d subsurface geophysical surveys were performed using a ground penetrating radar system toAuthorsD. Mallinson, S. Mahan, Christine MooreLate pleistocene aggradation and degradation of the lower colorado river: Perspectives from the Cottonwood area and other reconnaissance below Boulder Canyon
Where the lower Colorado River traverses the Basin and Range Province below the Grand Canyon, significant late Pleistocene aggradation and subsequent degrada tion of the river are indicated by luminescence, paleomagnetic, and U-series data and stratigraphy. Aggradational, finely bedded reddish mud, clay, and silt are underlain and overlain by cross-bedded to plane-bedded fine sand and silt. That sAuthorsS.C. Lundstrom, S. A. Mahan, J.B. Paces, M. R. Hudson, P.K. House, D.V. Malmon, J.L. Blair, K. A. HowardOptically stimulated luminescence age controls on late Pleistocene and Holocene coastal lithosomes, North Carolina, USA
Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2??ka. Oxygen-isotope dataAuthorsD. Mallinson, K. Burdette, S. Mahan, G. BrookA 3-Dimensional Model of Water-Bearing Sequences in the Dominguez Gap Region, Long Beach, California
A 3-dimensional computer model of the Quaternary sequence stratigraphy in the Dominguez gap region of Long Beach, California has been developed to provide a robust chronostratigraphic framework for hydrologic and tectonic studies. The model consists of 13 layers within a 16.5 by 16.1 km (10.25 by 10 mile) square area and extends downward to an altitude of -900 meters (-2952.76 feet). Ten sequencesAuthorsDaniel J. Ponti, Kenneth D. Ehman, Brian D. Edwards, John C. Tinsley, Thomas Hildenbrand, John W. Hillhouse, Randall T. Hanson, Kristen McDougall, Charles L. Powell, Elmira Wan, Michael Land, Shannon Mahan, Andrei M. Sarna-WojcickiLate quaternary paleoseismology of the southern Steens fault zone, northern Nevada
The 192-km-long Steens fault zone is the most prominent normal fault system in the northern Basin and Range province of western North America. We use trench mapping and radiometric dating to estimate displacements and timing of the last three surface-rupturing earthquakes (E1-E3) on the southern part of the fault south of Denio, Nevada. Coseismic displacements range from 1.1 to 2.2 ?? 0.5 m, and rAuthorsS. F. Personius, A. J. Crone, M. N. Machette, S. A. Mahan, J.B. Kyung, H. Cisneros, D. J. LidkePaleoecology reconstruction from trapped gases in a fulgurite from the late Pleistocene of the Libyan Desert
When lightning strikes the ground, it heats, melts, and fuses the sand in soils to form glass tubes known as fulgurites. We report here the composition of CO2, CO, and NO contained within the glassy bubbles of a fulgurite from the Libyan Desert. The results show that the fulgurite formed when the ground contained 0.1 wt% organic carbon with a C/N ratio of 10-15 and a ??13C of -13.96???, compositioAuthorsGonzalez R. Navarro, S. A. Mahan, A.K. Singhvi, R. Navarro-Aceves, J.-L. Rajot, C.P. McKay, P. Coll, F. RaulinAn optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils
There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence dating the equAuthorsS. A. Mahan, D.J. BrownLate Quaternary stratigraphy and luminescence geochronology of the northeastern Mojave Desert
The chronology of the Holocene and late Pleistocene deposits of the northeastern Mojave Desert have been largely obtained using radiocarbon ages. Our study refines and extends this framework using optically stimulated luminescence (OSL) to date deposits from Valjean Valley, Silurian Lake Playa, Red Pass, and California Valley. Of particular interest are eolian fine silts incorporated in ground-watAuthorsS. A. Mahan, D. M. Miller, C. M. Menges, J.C. YountLuminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front
Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but their ageAuthorsM.F. Sohn, S. A. Mahan, J.R. Knott, D.D. BowmanNumerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-se
A Late Quaternary spit-shoreline complex on the northern shore of Pleistocene Lake Mojave of southeastern California, USA was studied with the goal of comparing accelerator mass spectrometry (AMS) radiocarbon, luminescence, electron spin resonance (ESR), terrestrial cosmogenic radionuclide (TCN) surface exposure, amino acid racemization (AAR) and U-series dating methods. The pattern of ages obtainAuthorsL.A. Owen, Jordon Bright, R.C. Finkel, M.K. Jaiswal, D. S. Kaufman, S. Mahan, U. Radtke, J.S. Schneider, W. Sharp, A.K. Singhvi, C.N. WarrenAges of Quaternary Rio Grande terrace-fill deposits, Albuquerque area, New Mexico
Results from luminescence dating on 13 samples from the Albuquerque area show that major-drainage fluvial deposits represent significant periods of aggradation that formed paired, correlatable terraces on the east and west margins of the Rio Grande valley . The youngest terrace fills (Primero Alto) formed during late Pleistocene as a result of streamflow variations with climate cooling during MariAuthorsShannon Mahan, Byron D. Stone, Ralph R. ShrobaDevelopment of spatially diverse and complex dune-field patterns: Gran Desierto Dune Field, Sonora, Mexico
The pattern of dunes within the Gran Desierto of Sonora, Mexico, is both spatially diverse and complex. Identification of the pattern components from remote-sensing images, combined with statistical analysis of their measured parameters demonstrate that the composite pattern consists of separate populations of simple dune patterns. Age-bracketing by optically stimulated luminescence (OSL) indicateAuthorsC. Beveridge, G. Kocurek, R.C. Ewing, N. Lancaster, P. Morthekai, A.K. Singhvi, S. A. Mahan
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