Neogene volcanic-hydrothermal activity and epithermal gold-silver mineralization in the Teshikaga district, eastern Hokkaido, Japan

手利地区新近纪热液活动，北海道东部的热液活动可分为三个阶段，第一阶段的热液活动主要与中性蚀变有关的安山质和英安质的喷出和侵入活动有关，第二阶段的热液活动主要与中性蚀变有关的安山质侵入活动和3.2- 3.5 μ m的阿寒低温热液金银矿化有关，第三阶段的热液活动主要与中性蚀变有关的安山质侵入活动有关，第四阶段的热液活动主要与中性蚀变有关的安山质侵入活动有关。第三期热液活动主要与安山质和英安质侵入和喷出活动有关，特别是相对广泛的安山质火山活动，与2.2Ma的中性蚀变和Tobetsu浅成热液金有关，2.4Ma的银化与大鹏存款的Kanehana、Kinshu和Zuiho浅成热液金银矿化有关，也与2.3Ma的Shikerepeama酸性蚀变相关的相对局部的英安质火山活动有关。

Neogene hydrothermal activity in the Teshikaga district, eastern Hokkaido can be classified into three stages.Stage I hydrothermal activity is related to andesitic and dacitic extrusive and intrusive activities associated mainly with neutral alteration.Stage II hydrothermal activity is related mainly to andesitic intrusive activity associated with neutral alteration and the Akan epithermal gold-silver mineralization of 3.2-3.8 Ma and the Motoyama and Takinosawa epithermal gold-silver mineralizations of the Taiho ore deposit.Stage III hydrothermal activity is related mainly to andesitic and dacitic intrusive and extrusive activities, especially relatively widespread andesitic volcanic activity associated with neutral alteration of 2.2 Ma and the Tobetsu epithermal gold-silver mineralization of 2.4 Ma and the Kanehana, Kinshu and Zuiho epithermal gold-silver mineralizations of the Taiho ore deposit and also is related to relatively local dacitic volcanic activity associated with the Shikerepeyama acid alteration of 2.3 Ma.