International collaborative research on tephrology, archeology and paleoecology on the Aleut ruins in the western part of the Fox Islands, Alaska

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K01239
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Geography
• Research Institution: Fukuoka University
• Principal Investigator: Okuno Mitsuru 福岡大学, 理学部, 教授 (50309887)
• Co-Investigator(Kenkyū-buntansha): 中村 俊夫 名古屋大学, 宇宙地球環境研究所, 招へい教員 (10135387) ; 佐藤 鋭一 大阪府立大学, 理学(系)研究科, 准教授 (40609848)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: テフラ / アレウト / 火山噴火 / 考古遺跡 / 放射性炭素年代 / アナングラ島 / ウムナック島 / ウナラスカ島

Outline of Final Research Achievements

The oldest Aleutian archeological site (about 8400 BP) is located on Anangula Island, roughly 7 km north of Nichoski, on the southwestern end of Umnak Island in the Fox Islands. We collaborated with Dr. Hatfield of the Museum of the Aleutians and Dr. Savinetsky of the Russian Academy of Sciences to excavate a 1.7 m deep peatland deposit on Anangula Island. Coarse-grained tephras identified at a depth of 1.5 m and 0.7 m (tentatively called T-1, T-2) are both composed of andesitic rock fragments and free crystals. They contain plagioclase, orthopyroxene, augite, and Fe-Ti oxides. Although they are correlated with Ash III and Ash IV around Nikolski, the radiocarbon ages obtained are much younger than the ages estimated from these tephras. The peat layer upstream of the Iliuliuk River on Unalaska Island dates to the early Holocene.

Free Research Field

自然地理学，火山学，第四紀学，放射性炭素年代学，自然災害科学

Academic Significance and Societal Importance of the Research Achievements

この研究は，テフラ学・考古学・古生態学の学際的研究によってアレウト最古の考古遺跡を再検討するもので，アリューシャン博物館のHatfield博士やロシア科学アカデミーのSavinetsky博士らとの日米露の国際共同研究により実施した．北限近傍の環境変遷と火山噴火が，アレウトの拡散展開にどのように影響を与えたかを議論し，アーカイブとしての考古遺跡の保存についても検討している．