Additional Information

Select Bibliography:

Evans, William C., Bergfeld, Deborah, McGeehin, John P., King, John C. and Heasler, Henry, 2010, "Tree-ring ¹⁴C links seismic swarm to CO₂ spike at Yellowstone, USA", Geology, v.38, no. 12, pp. 1075-1078.

Miller, David M., Schmidt, Kevin M., Mahan, Shannon A., McGeehin, John P., Owen, Lewis A., Barron, John A., Lehmkuhl, Frank and Lohrer, Rene, 2010, Holocene landscape response to seasonality of storms in the Mojave Desert, Quaternary International, v. 215, Issues 1-2, pp. 45-61.

Markewich, Helaine, Gary R. Buell, Louis D. Britsch, John P. McGeehin, John A. Robbins, John H. Wrenn, Douglas L. Dillon, Terry L. Fries, and Nancy R. Morehead, 2006, Soil Organic Carbon Sequestration in the Mississippi River Deltaic Plain - Landscape Distribution, Accumulation Rates, Storage, Inventory, and Recent Loss (including a post-Katrina preliminary analysis), U.S. Geological Survey Professional Paper 1686.

McGeehin, J., Burr, G.S., Jull, A.J.T., Reines, D., Gosse, J., Davis, P.T., Muhs, D., Southon, J.R., 2001, "Stepped-Combustion ¹⁴C Dating of Sediment: A Comparison With Established Techniques", Radiocarbon, 43(2A), p. 255-261.

Radiocarbon Dating

Carbon extraction line. Sample CO2 gas is reduced to pure carbon as graphite precipitated on iron powder for dating by accelerator mass spectrometry.

Carbon extraction line. Sample CO₂ gas is reduced to
pure carbon as graphite precipitated on iron powder
for dating by accelerator mass spectrometry.

The objective of this Lab is to provide prompt, accurate and precise radiocarbon (¹⁴C) accelerator mass spectrometry (AMS) analyses on a wide variety of geologic materials in support of Climate and Land Use Change research. Support also is provided to other USGS mission areas as resources permit. Sample selection and analysis is carried out in close contact with project scientists. Established analytical procedures for radiocarbon dating are carefully applied to every sample the laboratory processes. New methods are developed and tested as necessary to meet specific dating needs and to improve the overall accuracy and precision of the lab.

Why is this research important?

Radiocarbon dating by accelerator mass spectrometry (AMS) is an important analytical method utilized in climate change, land use change, ecosystems and natural hazards research. As a chronology tool, ¹⁴C dating can provide ages for samples as old as 50,000 years. The small sample size capability of AMS radiocarbon dating greatly expands the potential for dating geologic material previously undateable using older proportional counting methods. The Reston radiocarbon laboratory performs research in the accurate ¹⁴C dating of different fractions of carbon that can be isolated from organic compounds such as sediments, soils and peat, which are often difficult to date reliably.

Principal Investigator: John P. McGeehin

Project Team: Timothy Muzik