2018 Volume 72 Issue 1 Pages 59-72
Various late- and post-Pliocene strata are distributed in the hills and along the rivers of the western Kanto Plain. We describe the YAO Tephra of the Hanno Formation, the SYG Tephra, the SGO Tephra in the Sayama Formation, and the SSI Tephra in the Bushi Formation. Through wide scale comparison, we were able to determine SYG is comparable to the approximately 1.7 Ma Tsuike Volcanic ash Layer (TsA) distributed in the Niigata region. The SGO Tephra 20 m above the SYG Tephra is correlative to the E1 Tephra in the Bushi Formation and to the HU
1 Tephra in the Tama Hills. The SSI vitreous tephra found just below the E1 Tephra is correlative to the HU2 Tephra of the Tama Hills, and also correlative to the Kd25
Tephra of the Boso Peninsula aged about 1.65 Ma.
The tephrostratigraphy of western part of the Kanto Plain can be described in detail. We discuss the tectonics of the western part of the Kanto Plain by comparing sedimentary age, and dip and strike of each stratum. As a result, we consider that there was remarkable uplift of the Kanto Mountains 2.6-2.5 Ma, supplying a thick layer of sediment from the Kanto Mountains to the Kanto Plain, and this is still underway.
