To extract radiogenic argon from micas and to purify extracted gases, an apparatus was constructed. The procedures for the extraction and the purification were described. Purified gases were analysed by a mass spectrometer and methane and helium were observed as main components of their impurities. Extracation efficiency of radiogenic argon from the muscovite(Mt. Ishikawa, 16-80 mesh)was studied and it was seen that among the total argon extracted during 20hours' heating at 1100°C, more than 99 percent was extracted in 10 hours. Quantitative analyses of radiogenic argon with two kinds of Japanese mica (Mt. Ishikawa, Fukushima-ken and Mt. Daiichi-suisho, Fukushima-ken) and M. I. T. standard biotite 3203 were carried out isotope dilution method. Quantities of radiogenic argon per one gram of these micas were 3.65×10
-5cc STP, 2.84×10
-5cc STP and 3.87×10
-4 cc STP, respectively. K-Ar age of these two kinds of Japanese micas were estimated to be 1.3×10
8 years and 1.5×10
8 years respectively. The quantity of radiogenic argon in standard biotite 3203 obtained in this work were in good agreement with those reported by others.
View full abstract