D/H Ratios of Sericites from the Kamioka Mining Area

Abstract

D/H ratios of ten sericites from the Kamioka Zn-Pb skarn deposits and three pottery stone deposits nearby are measured. Their δD values are in the range from -100 to -120‰ (SMOW). Considering the fractionation between sericites and water at temperatures below 300°C, δD values of hydrothermal solutions responsible for the formation of these deposits are calculated to be about -70 to -90‰. These δD values are in harmony with the genetic hypothesis for the Kamioka deposits, which proposes a huge convective circulation of solutions of meteoric water origin at the time of latest Cretaceous.