[H-QR23] Diachronic dynamics of human-environment interactions

[HQR23-P07] The lower loam bed and eolian sand deposits found at Tomobe Hills, Middle Part of Ibaraki Prefecture

3-min talk in an oral session

*Shinzou OOI¹, Nobuo SAIRENJI², Tadayasu SUTO³, Hisao ANDO⁴ (1.GSI, 2.Shirakata Elementary School, 3.Kasama City, 4.Ibaraki University)

Keywords:Tomobe Hills, Eolian sand deposit, HBP Tephra, Tomobe Formation, Pleistocene

The Pleistocene Hikita and Tomobe formations are distributed in the Urizura and Tomobe hills and the Kakioka Basin,the midwestern part of Ibaraki Prefecture. Their sedimentary age remains undefined. As several tephra layers from the lower loam bed and eolian sand deposits overlying the Tomobe Formation were found at the Tomobe Hills, we examined their correlation. Two tephras possibly correlative with "GoP" and "HBP", key tephra beds of the Tama Loam in the Kanto Plain region, respectively were included in the lower loam bed. This indicates the lower stratigraphic position for the Tomobe Formation than the Jizodo Formation (equivalent to MIS11), Shimosa Group.