Paleocurrent and Petrographic Compositions of the Early Pleistocene Fukuji Tuff Breccia in Kami-takara Area, Central Japan

Abstract

Petrographic composition of the early Pleistocene Fukuji Tuff Breccia are comparable with the distribution of bedrocks in the area of Mt. Hotaka and the Hida Mountains to the east. Clast fabrics of the formation generally represent westward and southward paleocurrent directions. These facts indicate that in the early to middle Pleistocene, a “paleo-Azusa River”, by which the Fukuji Tuff Breccia was deposited, flowed westward from Kamikochi to Takayama. At that time, the volcanoes around Mt. Yake were much lower in elevation than at present.