岐阜県森ノ下遺跡出土の縄文土器に付着した炭化物の加速器による放射性炭素年代測定
1990 年 28 巻 5 号 p. 389-397
詳細
1990 年 28 巻 5 号 p. 389-397
Radiocarbon ages have been measured for charred deposits on the surface of large-sized buried pottery jars (35-50cm in height, 30-40cm in diameter), which were collected during the 1986 excavation at the Morinoshita site, one of the archeological sites in Asahi-mura, Ohno-gun, Gifu Prefecture, using a Tandetron accelerator mass spectrometer at the Radioisotope Center, Nagoya University. According to archeological estimates, the buried jars were used in the Jomon period, first as vessels for boiling foods such as gathered nuts and vegetables and hunted animals, and then as containers for burying the bodies of stillborn babies and infants, as well as placentae of newborns, at the entrances of dwellings.
The ages measured for the 10-300mg of charred materials, most likely the food residues of ancient people, collected from the surface of each of seven pottery jars ranged from 3, 940 to 4, 450y.B.P. The average of the seven ages was 4, 180±90y.B.P. In addition, wood charcoal collected in an excavation of the residence site at Morinoshita, which had probably been used as part of the wood materials for constructing a house, was dated as 4, 140±140y.B.P. These dates suggest that the pottery jars were used, and the house built, in the late part of the Middle Jomon. This estimation is consistent with the results from typological studies of the jars: some of the jars have been identified as belonging to the Sori-III type (late Middle Jomon).
Stable-isotope ratios of carbon (13C/12C) have also been measured for four samples of the carbonaceous residues on the inner surface of the pottery jars to investigate the diet in the Jomon period, yielding δ13CPDB values from -24.0 to -25.6‰. The δ13CPDB values suggest that C3 plants, which use the Calvin-Benson photosynthetic pathway, and animals feeding on C3 plants can be the sources of the carbonaceous residues, but that the contributions to such residues from C4 plants (the Hatch-Slack photosynthetic pathway), animals feeding on C4 plants, and seafood may be negligible.
