太平洋最北端のアリューシャン列島海域の海洋炭素リザーバー効果の評価と海産物試料の暦年較正

Abstract

To analyze important and substantial contributions of ancient Aleut peoples on the migration from the old land, Siberia, to the new land, American continent, just at the ending stage of the last glacial period, we are planning to set up a chronology of early Aleut settlements in the Aleutian archipelago by radiocarbon dating. Based on the accurate ages of terrestrial (plant residue) and oceanic (shell fossil) remains that were excavated for the archaeological sites on the Aleutians, we need to certificate the evidences of early Aleut settlements. To evaluate reliable historical age of the archeological remains, radiocarbon ages obtained must be calibrated to calendar year with a reliable method. 14C age of terrestrial sample is calibrated with IntCal20. That of marine residue with Marine20, with a local marine reservoir correction value (ΔR), estimated in advance for the particular ocean area. Thus, the radiocarbon ages of oceanic samples (shell fossil) must be analyzed carefully in the course of calibration, from 14C ages to calendar dates of the samples, because the initial radiocarbon contents of oceanic samples fluctuate considerably dependent on the ocean area where the samples were born and grown up. We therefore organized that in analyzing radiocarbon ages of oceanic samples from the Aleutians, we in advance tested the apparent radiocarbon age differences between terrestrial (plant residue) and oceanic (shell fossil) samples that were formed at the same period in the Aleutian area. The present research is an attempt for establishing a method to obtain accurate calendar ages and finally the robust chronology of the archeological sites on the Aleutians.departmental bulletin pape