Numerical dating algorithms of amino acid racemization ratios fromcontinental ostracodes:application to the Guadix-Baza Basin(southern Spain)

Abstract

Age calculation algorithms for the D/L ratios of five amino acids (isoleucine, leucine, aspartic acid, phenylalanine and glutamic acid) analysed in continental ostracodes were determined for southern and central Iberian Peninsula, and allow the numerical dating of deposits in the Mediterranean area since Lower Pleistocene time to present. In order to obtain more accurate results for young samples, other algorithms were calculated for aspartic acid, phenylalanine and glutamic acid. Using these algorithms, together with paleomagnetism, the chronostratigraphy of the "composite-stratotype-section" of the east domain of the Guadix-Baza Basin that covers most of the Pleistocene (from the Plio/Pleistocene boundary to 279 + 77ka) has been obtained. Ostracodes represent a formidable tool for amino acid racemization dating purposes in view of their abundance, valves mineralogy and the high degree of preservation of amino acids within their caparaces, even in old (Early Pleistocene) samples. These results suggest that the range of the amino acid racemization dating method in the Iberian Peninsula is older than 1.1 Ma.