Shannon Mahan

Biography

I graduated from Adams State University (Colorado) with a B.S. in Geology in 1987.  I immediately began work at the USGS with the Isotope Branch of Geology/Yucca Mountain Project as a Physical Science Technician. In 1991 I was converted to Geologist, in 1994 to Hydrologist, in 1999 back to Geologist, and in 2006 to Research Geologist.  From 1987 to 2017 I have worked with Radiogenic Isotopes, Thermoluminescence (TL), Optically Stimulated Luminescence (OSL), Radiation Dosimetry, and maintaining a sense of humor.  I have been the USGS Luminescence Geochronology Lab Director since 1997 and routinely work on 20 to 30 projects during the year throughout the USGS mission areas.

Over the past 35 years, luminescence dating has become a key tool for dating sediments of interest in paleoseismic research. The data obtained from luminescence dating has been used to determine timing of fault displacement, calculate slip rates, and estimate earthquake recurrence intervals. Luminescence is also used to date paleontology sites, fluvial terraces (including paleoflood deposits), eolian deposits, and is increasingly used to calibrate wildfire temperatures and thermochronology. The flexibility of luminescence is a key complement to other chronometers such as radiocarbon or cosmogenic nuclides. Careful sampling and correct selection of sample sites exert two of the strongest controls on obtaining an accurate luminescence age. Factors such as partial bleaching and post-depositional mixing should be avoided during sampling and special measures may be needed to help correct for associated problems. Like all geochronologic techniques, context is necessary for interpreting and calculating luminescence results and this can be achieved by supplying participating labs with associated trench logs, photos, and stratigraphic locations of sample sites. (Taken from Gray et al, 2015 paper GUIDE TO LUMINESCENCE DATING TECHNIQUES AND THEIR APPLICATION FOR PALEOSEISMIC RESEARCH).

I provide age constraints on Quaternary deposition for a variety of eolian, fluvial, alluvial and lacustrine systems by dating sediment grains of alkali potassium feldspar (preferably orthoclase, microcline, and sanidine) using infrared stimulated luminescence (IRSL) or quartz using blue light stimulated luminescence (OSL).  As the only USGS luminescence dating specialist, I am 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.  I have supervised the growth and development of the USGS Luminescence Geochronology Lab (established in 1990) by mentoring many students, expanding corroborative and collaborative projects with private companies and universities, instituting new work with state geological surveys via STATEMAP or EDMAP, organizing workshops for both USGS and non-USGS personnel, and hosting distinguished foreign scientists.

As well as doing routine dating for a variety of USGS projects, I have provided luminescence expertise for many larger USGS efforts with a dramatic increase in real-time data availability and publication of results (i.e. new technology with a portable OSL reader). I have provided detailed analyses, evaluations, and/or reviews of OSL data to such entities as the National Science Foundation (NSF), The Army Research Office, the Army Corps of Engineers, The Bureau of Reclamation, The National Park Service, and many state geological surveys and departments of natural resources.  I have also initiated collaborative work and grants with other luminescence dating labs in the US by providing expert review on grant proposals, second-opinion elemental dosimetry regarding possible disequilibrium, and first refusal for many novel or cutting applications as applied to luminescence dating (which helps provide outside funding).  Other scientists routinely seek my advice in luminescence dating and I receive at least ten inquiries a week related to questions of luminescence dosimetry, usually via the USGS luminescence dating website. http://gec.cr.usgs.gov/projects/lumlab/ 

 

Other Publications (see tab below for main list)

Sherrod, B.L., Blakely, R.J., Lasher, J.P., Lamb, A., Mahan, S.A., Foit, F.F., Barnett, E.A., 2016, Active faulting on the Wallula fault zone within the Olympic-Wallowa Lineament, Washington State, USA, GSA Bulletin, in press.

Dragovich, J.D.; Mahan, S.A.; Anderson, M.L.; MacDonald, J.H., Jr; Schilter, J.F.; Frattali, C.L.; Koger, C.J., Smith, D.T.; Stoker, B.A.; DuFrane, A.; Eddy, M P.; Cakir, R.; Sauer, K.B., 2015, Geologic map of the Lake Roesiger 7.5-minute quadrangle, Snohomish County, Washington: Washington Division of Geology and Earth Resources Map Series 2015-01, 1 sheet, scale 1:24,000, 47 p. text.   [http://www.dnr.wa.gov/publications/ger_ms2015-01_geol_map_lake_roesiger_24k.zip]

DeJong, B.D., Bierman, P., Newell, W.L., Rittenour, T.M., Mahan, S.A., Balco, G., Hood, D.R., 2015, Pleistocene relative sea levels in the Chesapeake Bay region and their implications for the next century, GSA Today 25 (8), p. 4-10.  http://www.geosociety.org/gsatoday/archive/25/8/article/i1052-5173-25-8-4.htm

Mahan, S.A., Nelson, M., Rittenour, T. M., Hanson, P. R., and Rhodes, E.G.., 2015, The 9th New World Luminescence Dating Workshop: aim of the community and scope of the conference proceedings, USA, Quaternary International 362, 1-2. [Link]

Peek, K.M., Mallinson, D.J., Culver, S.J., and Mahan, S.A., 2014. Holocene geologic development of the Cape Hatteras region, Outer Banks, North Carolina, USA, Journal of Coastal Research 30 (1), 41-58. [Link]

Dragovich, J. D.; Frattali, C. L.; Anderson, M. L.; Mahan, S. A.; MacDonald, Jr., J. H.; Stoker, B. A.; Smith, D. T.; Koger, C. J.; Cakir, R.; DuFrane, S. A.; Sauer, K. B., 2014, Geologic map of the Lake Chaplain 7.5-minute quadrangle, Snohomish County, Washington: Washington Division of Geology and Earth Resources Map Series 2014-01, 1 sheet, scale 1:24,000, 51 p. [Link]

Swezey, C.S., Schultz, A.P., Gonzalez, W.A., Bernhardt, C.E., Doar, W.R., Garrity, C.P., Mahan, S.A., and McGeehin, J.P., 2013, Quaternary eolian dunes in the Savannah River Valley, Jasper County, South Carolina, USA, Quaternary Research 80 (2), 250-264. [Link]

Amos, Colin, Lutz, Andrew, Jayko, Angela, Mahan, Shannon, Fisher, G. B., Unruh, Jeffrey, 2013, Refining the southern extent of the 1872 Owens Valley earthquake rupture through paleoseismic investigations in the Haiwee Area, southeastern California, Bulletin of the Seismological Society of America 103 (2A), 1022-1037. [Link]

Rizza, Magali, Vernant, Phillippe, Ritz, Jean-Francois, Peyret, Michel, Nazari, Hamid, Nankali, Hamid, Djamour, Yahya, Salamati Reza, Mahan, Shannon, Masson, F., 2013, Morphotectonics and geodetic evidences for a constant slip-rate over the last 45 kyr along the Tabriz Fault (Iran), Geophysical Journal International, June 2013 193 (3), 1083-1094. [Link]

Dragovich, J. D., H. A. Littke, S. A. Mahan, M. L. Anderson, J. H. MacDonald Jr., Recep Cakir, B. A. Stoker, C. J. Koger, J. P. Bethel, S. A. DuFrane, D. T. Smith, and N. M. Villeneuve, 2013, Geologic map of the Sultan 7.5-minute quadrangle, King and Snohomish Counties, Washington. 2013. 44 x 36 in. color plate, scale 1:24,000, with 52 p. text. [Link]

Washington State Department of Natural Resources Open File Report 2012-1. Dragovich, J. D.; Anderson, M. L.; Mahan, S. A.; MacDonald, J. H., Jr.; McCabe, C. P.; Cakir, Recep; Stoker, B. A.; Villeneuve, N. M.; Smith, D. T.; Bethel, J. P., 2012, Geologic map of the Lake Joy 7.5-minute quadrangle, King County, Washington: Washington Division of Geology and Earth Resources Map Series 2012-01, 2 sheets, scale 1:24,000, 79 p. text. [Link]

Washington State Department of Natural Resources 2011-1. Geologic map of the Monroe 7.5-minute quadrangle, King and Snohomish Counties, Washington, 2011, J. D. Dragovich, M. L. Anderson,S. A. Mahan, C. J. Koger, J. H. Saltonstall, J. H. MacDonald Jr., G. R. Wessel, B. A. Stoker, J. P. Bethel, J. E. Labadie, Recep Cakir, J. D. Bowman, and S. A. DuFrane, 42 x 36 in. color sheet, scale 1:24,000, with 24 p. text. [Link]

Washington State Department of Natural Resources Open File Report 2011-2. Analytical data from the Monroe 7.5-minute quadrangle, King and Snohomish Counties, Washington—Supplement to Open File Report 2011-1, by J. D. Dragovich, S. A. Mahan, M. L. Anderson, J. H. MacDonald Jr., G. R. Wessel, S. A. DuFrane, Recep Cakir, J. D. Bowman, and H. A. Littke. 61 p., 2 plates, and 2 Microsoft Excel files. [Link]

Open File Report 2010-5. Supplement to geologic maps of the Lilliwaup, Skokomish Valley, and Union 7.5-minute quadrangles, Mason County, Washington-Geologic setting and development around the Great Bend of Hood Canal, by Michael Polenz, T. A. Contreras, J. L. Czajkowski, Gabriel Legorreta Paulin, B. A. Miller, M. E. Martin, T. J. Walsh, R. L. Logan, R. J. Carson, C. N. Johnson, R. H. Skov, S. A. Mahan, and C. R. Cohan. 2010. 27 p. [Link]

Open File Report 2010-4. Geologic map of the Lilliwaup 7.5-minute quadrangle, Mason County, Washington, by T. A. Contreras, Gabriel Legorreta Paulin, J. L. Czajkowski, Michael Polenz, R. L. Logan, R. J. Carson, S. A. Mahan, T. J. Walsh, C. N. Johnson, and R. H. Skov. 2010. 27.5 x 36 in. color sheet, scale 1:24,000, with 13 p. text. [Link]

Open File Report 2010-3. Geologic map of the Skokomish Valley and Union 7.5-minute quadrangles, Mason County, Washington, by Michael Polenz, J. L. Czajkowski, Gabriel Legorreta Paulin, T. A. Contreras, B. A. Miller, M. E. Martin, T. J. Walsh, R. L. Logan, R. J. Carson, C. N. Johnson, R.H. Skov, S. A. Mahan, and C. R. Cohan. 2010. 42 x 36 in. color sheet, scale 1:24,000, with 21 p. text. [Link]

Open File Report 2010-2. Supplement to the geologic map of the Carnation 7.5-minute quadrangle, King County, Washington-Geochronologic, geochemical, point count, geophysical, earthquake, fault, and neotectonic data, by J. D. Dragovich, M. L. Anderson, J. H. MacDonald Jr., S. A. Mahan, S. A. DuFrane, H. A. Littke, G. R. Wessel, J. H. Saltonstall, C. J. Koger, and Recep Cakir. 2010. 42 p. with 8 digital appendices. [Link]

Open File Report 2010-1. Geologic map of the Carnation 7.5-minute quadrangle, King County, Washington, by J. D. Dragovich, H. A. Littke, M. L. Anderson, G. R. Wessel, C. J. Koger, J. H. Saltonstall, J. H. MacDonald Jr., S. A. Mahan, and S. A. DuFrane. 2010. 42 x 36 in. color sheet, scale 1:24,000, with 21 p. text. [Link]

Lundstrom, S.C., Paces, J.B., Mahan, S. A., Page, W. R. and Workman, J.B., 1999, Quaternary Geologic mapping and geochronology of the Las Vegas 1:100,000 sheet and Yucca Mountain area-Geomorphic and Hydrologic response to climate change near Death Valley: U.S. Geological Survey Open-File Report 99-153, p. 110-111.

Paces, J.B., Whelan, J.F., Forester, R.M., Bradbury, J.P., Marshall, B.D. and Mahan, S.A., 1997, Summary of Discharge Deposits in the Amargosa Valley: U.S. Geological Survey Administrative Milestone Report SPC333M4 to DOE. 

Lundstrom S.C., Whitney J.W., Paces J.B., Mahan, S.A. and Ludwig, K.R, 1995, Preliminary surficial deposits map of the southern half of the Busted Butte 7.5 quadrangle, Nye County, Nevada: U.S. Geological Survey Open-File Report 95-311, 2 sheets.

Lundstrom S.C., Mahan, S.A. and Paces, J.B., 1995, Preliminary surficial deposits map of the northwest quarter of the Busted Butte 7.5 quadrangle, Nye County, Nevada: U.S. Geological Survey Open-File Report 95-133, 2 sheets.

Paces J.B, Mahan, S.A., Kwak, L., Neymark, L.A., McConnaughey, E.A, and Bush, C.A., 1995, Preliminary Age Estimates for Late Pleistocene Ground-water Discharge Deposits near Yucca Mountain, Nevada: U.S. Geological Survey Open-File Report 94-703, 89 p.

Paces J.B, Mahan, S.A., Ludwig, K.R., Kwak, L., Neymark, L.A., Simmons, K.R., Nealy, L.D., Marshall, B.D. and Walker, A., 1995, Progress Report on Dating Quaternary Surficial Deposits: 1995 Milestone report 3GCH510M.

Singer, F.T., Dickerson, R.P., Olsten, M.J., and Mahan, S.A., 1995, Geochemistry of borehole samples from USW G-1 and USW G-3/GU-3, Yucca Mountain, Nevada: U.S. Geological Survey Open-File Report 95-54, 133 p.

Peterman Z.E., Spengler R.W., Futa K., Marshall B.D., and Mahan, S.A., 1991, Assessing the natural performance of felsic tuffs using the Rb-Sr and Sm-Nd systems study of the altered zone in the Topopah Spring Member, Paintbrush Tuff, Yucca Mountain, Nevada: Materials Research Society Symposium Proceedings, vol. 212, p. 687-694.