Ore mineralogy and formation condition of epithermal gold-silver deposits in the southwestern Hokkaido Japan
Ore mineralogy and formation condition of epithermal gold-silver deposits in the southwestern Hokkaido Japan
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日本北海道西南部浅成热液金银矿床矿石矿物学及形成条件
DOI：
10.1016/j.proeps.2013.01.014
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
H.
中科院分区：
文献类型：
--
作者：
Yuningsih;E.;T. and Matsueda;H.
北海道西南部矿区以盛产新近系第三纪浅成热液矿床而闻名。研究了北海道西南部的神北泽、新Otoyo、Suttsu、千岁、Teine、Date、Koryu和Toya等浅成低温热液型金银矿床的矿石矿物组合。其矿物组合的测定是基于对北海道西南部野外工作中收集的样品和北海道大学博物馆收藏的样品的研究。结合显微镜、电子显微探针和基于bse的抛光切片图像分析来评估矿石矿物的化学成分。北海道西南部岩浆-热液体系中的金银大部分富集碲化物和含te矿物，是矿石中贵金属的主要载体。其他矿物为硫化物、硫酸盐和氧化物类矿石，但各矿床的矿石矿物组合存在一定差异。部分矿床中存在辉铝岩或黄褐铁矿，表明其沉积处于高硫化状态，属于浅成热液型成矿类型。石英等脉石矿物中流体包裹体的均一温度和矿化度的测量表明，这些矿床的形成温度一般在170 ~ 260℃之间，矿化度小于4wt。% NaClequiv。某些矿床流体包裹体中的沸腾迹象表明，这种现象可能影响矿石的沉淀。
The southwestern Hokkaido mining district is well known for the occurrence of many epithermal ore deposits ofNeogene Tertiary period.The ore mineral assemblages in the epithermal gold-silver deposits from the southwestern Hokkaido such as Kobetsuzawa, Shin Otoyo, Suttsu, Chitose, Teine, Date, Koryu and Toya mines are examined. The determinations of their minerals assemblages are based on the study of samples collected during field works in the southwestern Hokkaido and from the Hokkaido University Museum collection. Combinations of microscopic, electron-microprobe, and BSE-based image analyses of polished sections were used to evaluate the chemical composition of ore minerals. Most of gold-silver in the magmatic-hydrothermal systems of the southwestern Hokkaido are enriched in tellurides and Te-bearing minerals, suggesting major carriers of precious metal in the ore. Other minerals are sulfides, sulfosalts and oxides group of ores, although each deposit is characterized by the occurrence of some difference ore minerals assemblages. The presences ofenargite or famatinite in some deposits suggest the deposition in the higher sulfidation state of epithermal mineralization style. The measurement ofhomogenization temperature and salinity of fluid inclusions in some gangue minerals such as quartz associated with ores from those deposits suggest that the formation temperature in general are around 170 — 260°Cwith salinity less than 4wt.% NaClequiv.Boiling indications in fluid inclusions of some deposits give the possibility this phenomenainfluence to the ore precipitation.