群馬県南東部八王子丘陵周辺に分布する凝灰岩類のフィッショントラック年代

Fission track dating of five tuffs distributed along the Hachioji Hills and its surrounding area in the southeastern part of Gunma Prefecture was researched. As a result, the age of the Mamioka Tuff which had never been reported using radiometric age was clarified. The age values of 3 samples of the Yabuzuka Formation were almost similar. It is suggested that the Yabuzuka Formation is over the Midorimachi Formation because it shows the younger age than the Midorimachi Formation, which was reported to be covered the Yabuzuka Formation. The Kanayama Welded Tuff was older than the age value reported so far, but because the χ^2 test value is low, it is a reference value.