Details

Autor(en) / Beteiligte

• Komatsubara, Taku
• Hongo, Misao
• Furusawa, Akira

Titel

The early last glacial fill terrace along the upper reach of the Sotoyama River (Ooishi River), in the Northern Kitakami Mountains, northeast Honshu Island, Japan

Ist Teil von

• The Quaternary Research (Daiyonki-Kenkyu), 2024, pp.63.2220

Ort / Verlag

Japan Association for Quaternary Research

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• There is a distinct fill terrace along the uppermost course of the Sotoyama River, in northern part of the Kitakami Mountains, northeast Honshu. The terrace deposits are mainly made up of thick stratified and imbricated sand and gravel layers interfingered with lenticular silt and humic silt layers, and they are accompanied with a clay layer in the top part. This terrace is located ca. 700 m above sea level, and in the coolest area in Honshu Island. The Towada-Oofudo tephra (ca. 36 cal ka BP) is found in the upper clay layer. Pollen assemblages in five silty and clayey layers indicate that mixed broadleaf-conifer forest vegetation had been dominant during the whole duration of the deposition of the fill terrace deposits. This paleo-vegetation shows a cooler climate than Holocene but a milder climate than the LGM. The coarse gravelly sediments were deposited not by periglacial processes but by running water from the later stage of the last interglacial age (MIS 5 d) to a stadial in the early last glacial age (MIS 4-3), and supply of them from mountain slopes had stopped in the early stage of the LGM. The volume of sediments of this fill terrace in the uppermost course of the Sotoyama River is estimated to be much less than the volume which is supplied from watershed mountain slope area during the deposition of the fill terrace. It suggests that huge amount of clasts had run off from the uppermost course of this river and formed a fill terrace along middle course of river.