Pre-bomb marine reservoir ages in the western north Pacific:Preliminary result on Kyoto University collection

The calibration of radiocarbon dates on marine materials involves a global marine calibration with regional corrections. The marine reservoir ages in the Western North Pacific have not been discussed, while it is quite important to determine the timing of palaeo-environmental changes as well as archaeological interpretation around this region. The lack of adequate collection of the pre-bomb shell from western north Pacific was the biggest problem. Recently we had a chance to examine specimens from an old shell collection stored in Kyoto University, including shell specimens from Japan, Korea, Taiwan and the Micronesia of 1920s and 1930s. We explored the possibility for usage of specimen without clear evidence of live collection by measuring 30 apparent radiocarbon ages of pre-bomb mollusk shells from 18 sites in Western North Pacific. The preliminary results showed several discrepancies with previously reported results and with each other. We have to carefully select the shell specimen that has biological signs such as articulating fulcrum. In order to exploit this big resource of pre-bomb shell collection, the new technique to distinguish fossils from; live collected samples should be developed by using chemical and physical methods. (C) 2000 Elsevier Science B.V. All rights reserved.