17:15 〜 19:15
[U02-P07] 鹿児島県徳之島における下原洞穴遺跡出土試料を用いた古環境復元
キーワード：古環境、炭素年代測定、徳之島
The Nansei Islands, stretching about 1,100 km from Kyushu to Taiwan, are an important migration route into the Japanese archipelago and hold considerable anthropological significance (Kaifu et al., 2019). Numerous sites have been already excavated, such as Yamashita-cho1 ruins in Naha City, Okinawa, and Shiraho Saonetabaru Cave ruins in Ishigaki City, Okinawa. In Tokunoshima Island, excavation of the Isen-cho Omonawa shell mound began in 1930, with 138 sites identified by 2024. However, archaeological evidence from 30,000 to 20,000 years ago - when humans likely first arrived - remains scarce.
Paleoenvironmental studies in the Nansei Islands have focused on inland bay waters (Yamada et al., 2014), while terrestrial settings remain understudied. The Shitabaru Cave site in Amagi Town, Tokunoshima Island, Kagoshima Prefecture, preserves a sedimentary record spanning the past 30,000 years including the archaeological blank period (Amagi Town Board of Education, 2024). This site has yielded numerous traces of human activity, including human bones, faunal bones, and furnace traces, and is expected to clarify the vegetation and dietary patterns of terrestrial fauna during this poorly documented interval.
This study aims to reconstruct the paleoenvironment using chemical proxies, such as 14C and C/N, from materials at the Shitabaru Cave site. Radiocarbon dating, applicable to organic materials up to about 55,000 years old, will be combined with C/N ratio to indicate paleoenvironmental age. Since the site's sediments consist of Ryukyu Group limestones, pollen preservation is poor, making conventional pollen analysis unfeasible; hence, C/N ratio is used to infer local vegetation.
Paleoenvironmental studies in the Nansei Islands have focused on inland bay waters (Yamada et al., 2014), while terrestrial settings remain understudied. The Shitabaru Cave site in Amagi Town, Tokunoshima Island, Kagoshima Prefecture, preserves a sedimentary record spanning the past 30,000 years including the archaeological blank period (Amagi Town Board of Education, 2024). This site has yielded numerous traces of human activity, including human bones, faunal bones, and furnace traces, and is expected to clarify the vegetation and dietary patterns of terrestrial fauna during this poorly documented interval.
This study aims to reconstruct the paleoenvironment using chemical proxies, such as 14C and C/N, from materials at the Shitabaru Cave site. Radiocarbon dating, applicable to organic materials up to about 55,000 years old, will be combined with C/N ratio to indicate paleoenvironmental age. Since the site's sediments consist of Ryukyu Group limestones, pollen preservation is poor, making conventional pollen analysis unfeasible; hence, C/N ratio is used to infer local vegetation.