|
|
|
|
|
|
|
improving the reliability of amino acid GeochronologyProject Members:
DescriptionThe importance of a robust chronology for Quaternary sediments cannot be underestimated. In recent years advances have been made in Amino Acid Racemization (AAR; Penkman, 2005), combining the isolation of an 'intra-crystalline' fraction of amino acids by exhaustive bleach treatment of ground shell carbonate (Sykes et al., 1995) with a new Reverse-Phase High Pressure Liquid Chromatography (RP-HPLC) method (Kaufman & Manley, 1998). This combination of techniques results in the analysis of D/L values of multiple amino acids from the chemically-protected protein within the biomineral, enabling both decreased sample sizes and increased reliability. The intra-crystalline protein occurs within a 'closed system' during the burial history of the shell, vital for the application of this technique for geochronological purposes. Amino acid data obtained from the intra-crystalline fraction of calcitic biominerals indicate this to be a particularly robust repository for the original protein, with this coherent system maintained as far back as the Pliocene. We aim to develop amino-acid racemization (AAR) as a dating tool by: (1) using laboratory methods and computational chemistry to (a) establish a closed chemical system; (b) test non-linear models of decomposition kinetics; (c) develop methods of internal validation based on other amino acids; (2) testing the method on Pleistocene molluscs. projects
|
  
|