Gas and Fluid Inclusion Studies of the Granitic and Rhyolitic Rocks From the Bupyeong Silver Mine Area

부평 은광산 지역의 유문암질암과 화강암류의 가스 및 유체포유물 연구

  • Kim, Kyu Han (Department of Science Education, Ewha Womans University) ;
  • Ha, Woo Young (Department of Science Education, Ewha Womans University)
  • 김규한 (이화여자대학교 과학교육과) ;
  • 하우영 (이화여자대학교 과학교육과)
  • Received : 1997.11.25
  • Published : 1997.12.31

Abstract

Volcanic rocks including rhyolitic tuff, rhyolite and welded tuff in the Bupyeong silver mine area form a topographic circular structure which is interpreted as a resurgent caldera. Granitic rocks are emplaced inside and outside area of the circular structure. Pervasive silver mineralization took place in the rhyolitic rock of the southwestern margin of the caldera. Gas and fluid incluson studies were carried out to investigate the petrogenetic evolution and post-magmatic alteration for the rhyolitic and granitic rocks. Gas compositions are characterized by a low $CH_4/CO_2$ ratio (0.004-0.005) for rhyolitic and inside granitic rocks and a high $CH_4/CO_2$ ratio (0.01~0.29) for outside granitic rocks such as the Kimpo and Incheon granites. Homogenization temperature of solid daughter mineral bearing fluid inclusion (III and IV types) and two phase fluid inclusion (I and II types) for quartz in the Bupyeong granites range from 400 to $500^{\circ}C$ and 121 to $514^{\circ}C$, respectively. Salinties vary from 20 to 30 wt% NaCl for type III and IV inclusions and less than 20 wt % NaCl for type I and II inclusions. The fluid inclusion data shows a considerable influx of the meteoric water toward post magmatic alteration stage.

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Acknowledgement

Supported by : 교육부