Economic and Environmental Geology (자원환경지질)

The Korean Society of Economic and Environmental Geology (대한자원환경지질학회)
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Characteristics of Lode Development and Structural Interpretation for the High Au Contents within the Fault Gouge Zones in Jinsan Au Mine, Chungcheongnam-do

충남 금산 진산금광산의 광맥 발달특성과 단층점토에 농집된 고품위 금함량에 대한 구조지질학적 해석

  • Shin, Dongbok (Department of Geoenvironmental Sciences, Kongju National University) ;
  • Gwon, Sehyeon (Department of Earth & Environmental Sciences, Pukyong National University) ;
  • Kim, Young-Seog (Department of Earth & Environmental Sciences, Pukyong National University)
  • 신동복 (공주대학교 지질환경과학과) ;
  • 권세현 (부경대학교 지구환경과학과) ;
  • 김영석 (부경대학교 지구환경과학과)
  • Received : 2015.01.19
  • Accepted : 2015.04.28
  • Published : 2015.04.28
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Abstract

Jinsan gold deposit is a hydrothermal vein type deposit consisting of several fissure filling quartz veins developed within the Changri Formation of the Ogcheon Supergroup in Geumsan, Chungnam. This study is to provide an efficient exploration and development strategies based on the characteristics of the geology, geological structure, core logging, and ore vein occurrence and grade for the four pits (New pit, Main pit, Yanghapan pit and Teugho pit). Quartz veins are mostly developed with the strike of $N10^{\circ}-25^{\circ}W$ and $N5^{\circ}-20^{\circ}E$, and the thickness is in the range of 0.1~0.5 m, sometimes extending to over 1m. Although the quartz veins commonly form massive shape, they sometimes show zonal structure, comb structure as well as brecciated texture. Major ore minerals are pyrite and chalcopyrite, and pyrrhotite, sphalerite, galena, marcasite, electrum and chalcocite are also accompanied as minor phases. Gray and milky white quartz veins, which are occasionally crosscut by calcite vein, also include fluorite. Ore evaluations for the 22 samples revealed that the samples from the pits generally have very low Au contents, lower than 1 g/t, but some clay samples of drilled core show very high Au concentrations, up to 141 g/t, indicating that Au content is much higher within fault gouges rather than within fresh quartz veins. This may represent that gold might have been reworked and reprecipitated by hydrothermal fluids in association with reactivation of the faults, and thus suggest that ore occurrence in this deposit is very complex and irregular and therefore more precise and systematic exploration is required.

충청남도 금산에 위치한 진산금광산은 옥천층군에 속하는 창리층 내에 발달한 열극대를 충진한 수개 조의 석영맥으로 구성된 열수맥상광상이다. 본 연구에서는 신갱, 본갱, 양하판, 특호맥 등 4개의 주요 갱도를 대상으로 지질광상 및 지질구조조사, 시추코어 분석, 그리고 주요 광맥의 발달상태와 품위를 파악하여 향후 효율적인 탐사 및 개발 방향을 제시하고자 하였다. 석영맥들은 주로 $N10^{\circ}-25^{\circ}W$, $N5^{\circ}-20^{\circ}E$ 방향으로 우세하게 발달하며, 맥폭은 대부분 0.1~0.5 m로 1 m가 넘는 경우도 있다. 이들은 괴상을 이루기도 하나 누대구조, 빗구조, 각력상구조가 잘 발달한다. 광석광물로는 황철석, 황동석이 주를 이루며 자류철석, 섬아연석, 방연석, 백철석, 에렉트럼 및 소량의 휘동석이 수반된다. 회색내지 유백색의 석영맥에는 형석이 수반되기도 하며, 후기 방해석맥에 의해 절단되기도 한다. 총 22개 광석시료에 대한 품위분석 결과 갱내 시료의 경우 대부분 1 g/t 미만의 저품위를 보이나 시추코어의 점토질 시료는 최대 141 g/t에 이르는 고품위를 나타낸다. 즉 신선한 석영맥보다는 단층점토 부분에 금함량이 높게 나타나는 것이다. 이는 1차적인 광화작용 이후에 이들이 단층의 재활성과 관련된 열수작용에 의해 금이 재이동되어 침전되었을 가능성을 나타낸다. 이로 보아 진산광상은 구조적으로 복잡하고 불규칙한 광체 발달양상을 지시하며, 이에 따라 보다 정밀하고 체계적인 탐사가 이루어져야 함을 시사한다.

Keywords

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