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Dating deep-lake sediments by using amino acid racemization in fossil ostracodes

¹ Department of Geology and Department of Environmental Sciences, Northern Arizona University, Flagstaff, Arizona 86011, USA

The long-term rate of racemization for amino acids preserved in fossil ostracode shells was determined by using independently dated sediment cores from five deep lakes. The racemization rates for aspartic and glutamic acids in the common ostracode genus Candona were calibrated for the past 100 k.y., providing the basis for an age equation with a realistic age uncertainty of ±20%. The new age equation can be applied to other hypolimnic settings because the temperature below the thermocline of deep lakes from middle- and high-latitude regions can reasonably be assumed to remain close to 4 °C. The sample size required for analysis is an order of magnitude less than for ¹⁴C dating and presents new opportunities to date deposits that are organic-matter poor or those with large ¹⁴C reservoir effects.

Key Words: amino acid racemization • Quaternary geochronology • deep-lake sediment • ostracodes

This article has been cited by other articles:

				A.S. Jayko, R.M. Forester, D.S. Kaufman, F.M. Phillips, J.C. Yount, J. McGeehin, and S.A. Mahan Late Pleistocene lakes and wetlands, Panamint Valley, Inyo County, California Geological Society of America Special Papers, January 1, 2008; 439(0): 151 - 184. [Abstract] [Full Text] [PDF]