British Aggregates: An Improved Chronology of Using Amino Acid Racemization and Degradation of Intracrystalline Amino Acid

Author(s): K Penkman, M Collins, David Keen, Richard Preece

The project assessed the utility of a novel method of amino acid racemization analysis (Intracrystalline Protein Degradation, or IcPD, analysis of intracrystalline proteins) and interpretation on the calcitic opercula of the gastropod Bithynia. The new technique combines a Reverse-Phase High Pressure Liquid Chromatography method (Kaufman and Manley 1998) with the isolation of an ‘intra-crystalline’ fraction of amino acids by bleach treatment (Sykes et al 1995), resulting in the analysis of D/L values of multiple amino acids from the chemically protected organic matter within the biomineral, enabling both decreased sample sizes and increased reliability. This study has shown that the intra-crystalline fraction within calcitic fossils, such as the opercula of the freshwater prosobranch Bithynia, provides tighter clustering of amino acid data than obtainable from shells composed of aragonite (Penkman 2005). The study shows that, using the IcPD approach, it is possible to provide relative age estimates of different aggregate deposits in England, and to relate these ages to the marine oxygen isotope record, so that it is possible to link aggregates to specific phases of the British Quaternary, beyond that which is possible using radiocarbon dating. The work has enabled us to identify the earliest human occupation in northern Europe (Parfitt et al 2005).

Report Number:
Research Department Reports
Amino-acid Racemisation Geochronology


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