A Study of the Correlation between and Chronology of Sites of human Habitation and Volcanic Ejecta in the Izu Islands

在伊豆群岛的火山喷出物下，发现了许多绳纹时期及以后的遗址和遗迹。通过调查这些遗骸与喷出物之间的相关性和年代学，对伊豆群岛的温度年代学进行了研究。结果可以总结如下。1)在对伊豆群岛广泛分布的麻风进行检查之后。八州岛、三宅岛等地喷出物与Kikai-Akahoya火山灰（K-Ah）的地层关系。在八丈岛发现了aira - tanawa火山灰（AT）。2)根据其与伊豆群岛喷出物中发现的遗址和依赖物的地层关系。确定了纪开-阿卡霍屋火山灰代表了绳纹时代晚期的创床。3)根据火山地层学、广泛分布的火山、陶器类型和放射性碳定年法对东山火山的形成历史进行了研究，确定了该火山口的形成时间与21,000至22,000年前aira - tanawa火山喷发的时间非常接近。流纹岩和岱岩火山灰被认为起源于小津岛。二岛、贝黄酱岩将在未来成为伊豆岛重要的标志层。在伊豆半岛和博索半岛发现了来自伊豆群岛的Tephra fall。这将证明对研究这些地区的温度年代学有相当大的帮助。

Buried under the volcanic ejecta of the Izu Islands there have been discovered a great many sites and relics dating from the Jomon period and later. A study of the tephrochronology of the Izu Islands was undertaken by investigating the correlation between and chronology of these remains and the ejecta. The results may be summarized as follows.1)Following an examination of widespread tephra in the Izu Islands. the stratigraphic relationship between the ejecta and Kikai-Akahoya Volcanic ash(K-Ah) on Hachijo-Jima, Miyake-jima, et.al. was clarified, and Aira-Tanzawa volcanic ash (AT) was discovered at the Hachijo-jima.2)On the basis of its stratigraphic relationship with the sites and relies discovered in ejecta on the Izu Islands. it was ascertained that Kikai-Akahoya volcanic ash represents a maker bed for the late Initial Jomon period.3)Following an examination of the history of the formation of Higashi-yama on the basis of tephra stratigraphy, widespread tephra, earthenware types and radiocarbon dating, it was established that the caldera was formed at a time extremely close to the ejection of Aira-Tanzawa volcanic ash 21,000 to 22,000 years ago.4)The rhyolite and daite volcanic ash thought to originate from Kozu-shima. Ni-Jima, Bayonnaise Rocks will in the future serve as an important marker bed in Izu Island. Tephra fall from the Izu Islands was discovered in the Izu Peninsula and in the Boso peninsula. This should prove to be of considerable assistance in studies on tephrochronology of these regions.