On the Gypsum-Bearing Alteration along Some Epithermal Veins in Hokkaido

Abstract

Few attention has been paid to the sulfatization of the wall rock alteration by gypsum and barite along epithermal base-metal veins. In some of lead-zinc-bearing rhodochrosite veins, however, gypsum and barite are not rare in association with sericite-quartz aggregates and more intimately with kaolinite. Typical examples are observed on the hydrothermal zones of Senzai vein, Oe mine and Shinsei vein, Inakuraishi mine. Since gypsum is replaced by sulfide minerals and rhodochrosite, gypsum-bearing hydrotermal alteration together with kaolinization may have occurred in a sericite-quartz zone prior to the carbonatization and deposition of ore minerals.