Amino acid chronology in the fossil planktonic foraminifera, Pulleniatina obliquiloculata from Pacific Ocean

This study was undertaken to evaluate the accuracy of amino acid chronology using a first‐order kinetic model and was carried out using a fossil planktonic foraminifera, Pulleniatina obliquiloculata ( P. obliquiloculata ), in the sediment from the western equatorial Pacific Ocean. The extent of racemization reaction of aspartic acid and glutamic acid and the extent of epimerization reaction of isoleucine were measured and compared with reference ages obtained from 14 C dating and the distribution patterns of δ 18 O. The relationships between the extent of racemization/epimerization reaction of these amino acids and reference ages were linear along with a high correlation coefficient (r = 0.99–0.95), suggesting that amino acid chronology utilizing a first‐order kinetic model could be appropriate for determining geological ages ranging from the present to 10 6 yBP within the average errors of 4.5, 12.3, and 15.8% for Asp, GIu, and Ile, respectively.