Thermoluminescence (TL) dating using quartz grain was carried out for 6 samples for old deposits and 26 samples for yonger deposits of the Hakkoda Pyroclastic Flow Deposits. Obtained TL ages are 0.51-0.55 Ma (Average 0.53 Ma) for former ones and 0.19-0.29 Ma (Average 0.25 Ma) for latter ones. These TL ages are 20-40% younger than reported K-Ar ages of 0.65 Ma and 0.40 Ma, respectively. Possible systematic error sources for such age difference are annealing effect in paleodose measurement, radon escape in annual dose evaluation. Adding to other minor effects for systematic errors, TL ages obtained by our usual experiments may have 10-20% younger values than true ages. The difference between TL and K-Ar ages is futher problems but ordinaly K-Ar data of this age range are not so reliable.
The errors in measurements are 10-15%, which are calculated from both paleodose measurements and chemical analyses for anuual dose evaluation. In addition, 10% errors are expected in beta-rays contribution in annual dose evaluation. Summarized total error in measurements is about 20%.

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Ultramafic xenoliths occur in the Cenozoic alkali basalt from Kawashimo, Shimane Prefecture, SW Japan. These xenoliths are divisible into two Types, A and B, in terms of petrography. Ultramafics of Type A are derived from the mantle peridotite. They are characterized by the metamorphic textures and higher Mg/Mg+Fe ratios and equilibrium temperatures of constituent minerals. They consist of lherzolite, harzburgite and wehrlite. Ultramafic xenoliths of Type B are of cumulus mantle origin and show the cumulus and exsolution textures. They are composed of lherzolite, pyroxenite, websterite and dunite. Assembleage of ultramafic xenoliths are similar to those from Noyamadake and Kibi-kogen, but the constituent minerals from Kawashimo xenoliths have higher Mg/Mg+Fe than those from the others.

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和歌山県飯盛地域の三波川変成域から得られた2つの石英片岩中に, Mnに富むカルシックないしソデイック角閃石が見いだされた。随伴するアルカリ輝石も同じようにMnにやや富み,また,ざくろ石はスベッサルティンである。角閃石の組成は幅広く変動し,サブカルシック透閃石からワィンチ閃石をへてクロス閃石に及ぶ。ある角閃石の内部にMnOに著しく富む部分があり,それはタイロダイトの組成をもつ。

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