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D/H study on clay minerals from the Iwami Kuroko deposit, Shimane Prefecture, Japan.

1986; Japan Association of Mineralogical Sciences; Volume: 81; Issue: 8 Linguagem: Inglês

10.2465/ganko1941.81.302

1883-0765

Yoshimasu Kuroda, YOSHIHARU KIDA, Kôji Watanabe, Takeshi Oba, Sadao Matsuo,

Geochemistry and Geologic Mapping

There is no difference between the δD values of the water extracted from coexisting Mgchlorite and sericite in the Iwami Kuroko deposit. The average δD values of the minerals agree with each other in the range from - 49 to - 52‰. This indicates that there is no D/H fractiona-tion between Mg-chlorite and sericite under the hydrothermal condition. The δD value of the hydrothermal solution participated in the formation of these minerals is estimated to be - 10‰according to the fractionation factor determined by O'Neil and Kharaka (1976), or - 23 to - 26‰ according to that estimated from natural samples by Marumo et al. (1980). The value is completely different from that of the contemporary meteoric water in the mining district (average, - 51‰). The δD value of the water extracted from fluid inclusions in quartz from the ore-veins is - 58 to - 59‰, which is different from those estimated for the hydrothermal solution during the formation of chlorite and sericite. This may indicate that there was a time difference between formation of chlorite-sericite clay and quartz. δD values of waters released from chlorite-smectite mixed layer mineral, smectite, clinoptilolite and gypsum have also been measured. The δD values of the mixed layer minerals are rather reliable for estimating the δD value of hydrothermal solution, but those of smectite are not useful. The fractionation factors between clinoptilolite-water and gypsum-water are also estimated.