Radiocarbon age determination at Shizuoka University(2)

We report 26 radiocarbon age data using the benzene liquid scintillation method developed at Shizuoka University by FUKUHARA et al. (1995). Benzene was synthesized from the plant leaves, modern land-snails (shells and bodies), fossil land-snail shells, coral, wood, charcoal (Mt. Omuro) and a carbonate chimney (Mariana). The ^<l4>C activity was measured using a low background liquid scintillation counter (Aloka LSC LB-1) at the Radiocarbon Research Institute of Shizuoka University. β^--rays were counted with a window width 150-550 which regulated by TAKAHASHI (1996 MS). All samples were counted in turn, each for 20 minute and repeated 50 to 151 times in order to moniter the counter stability and obtain sufficient counts for statistical error estimation. Correction for δ^<l3>C value was carried out. The standard used was NIST oxaric acid SRM 4990C, and the half-life used to calculatc the ^<l4>C age (yr. B.P.) was based on Libby\u27s half-life (5,568 yr). The ^<l4>C age anomaly of modern land-snail shells in Kikai Island for Phaeohelix phaeogramma were 250-1060 yr. And 710±160 yr. B.P. for Acusta despecta kikaiensis. We could not determine the ^<l4>C age anomaly for Cyclophorus kikaiensis. The ^<l4>C age of charcoaled wood collected from the immediately beneath the lava flow of the Omuro Volcano was the first report of 3,710±95 yr. B.P.publishe