함안지역 함 동 광화작용의 지화학적 환경

Geochemical Environments of Copper-bearing Ore Mineralization in the Haman Mineralized Area

  • 최상훈 (충북대학교 지구환경과학과)
  • Choi, Sang-Hoon (Department of Earth & Environmental Sciences, Chungbuk National University)
  • 발행 : 2009.02.28

초록

함안광화대는 한반도 남동부 백악기 경상퇴적분지 내에 위치한다. 함안광화대에는 함동 다금속 열수 맥상 광화작용이 진행되어, 함동광물을 포함한 황화광물들과 철산화광물 및 황염광물 등이 열극을 충진하여 발달한 전기석, 석영 및 탄산염광물 맥 내에 산출한다. 본 광화대 내에는 군북, 제일군북 및 함안 광상 등이 분포한다. 광화대의 광화작용은 함철 및 함동 광화작용이 주로 진행된 광화 I 기와 주된 동광화작용이 진행되어 황화광물과 황염광물이 산출하는 광화 II 기 및 금속광물의 산출이 이루어지지 않은 방해석맥으로 이루어진 광화 III 기로 구분된다. 광물공생관계와 광물의 지화학적 조성특성 등이 고려된 열역학적 연구결과 주된 함동광물인 황동석의 침전은 약 $350^{\circ}C$ 에서 시작되어 약 $250^{\circ}C$ 까지 진행되었다. 동은 주로 염화복합체로 이동되었으며, 상기 온도의 냉각과정에 수반된 지화학적 환경요인 ($fs_2$, $fo_2$, pH 등)들의 변화에 의한 함동 염화복합체의 용해도 감소에 의하여 침전되었다.

The Haman mineralized area is located within the Cretaceous Gyeongsang Basin along the southeastern part of the Korean peninsula. Almost all occurrences in the Haman area are representative of copper-bearing polymetallic hydrothermal vein-type mineralization. Within the area are a number of fissure-filling hydrothermal veins which contain tourmaline, quartz and carbonates with Fe-oxide, base-metal sulfide and sulfosalt minerals. The Gunbuk, Jeilgunbuk and Haman mines are each located on such veins. The ore and gangue mineral paragenesis can be divided into three distinct stages: Stage I, tourmaline + quartz + Fe-Cu ore mineralization; Stage II, quartz + sulfides + sulfosalts + carbonates; Stage III, barren calcite. Equilibrium thermodynamic data combined with mineral paragenesis indicate that copper minerals precipitated mainly within a temperature range of $350^{\circ}C$ to $250^{\circ}C$. During early mineralization at $350^{\circ}C$, significant amounts of copper ($10^3$ to $10^2\;ppm$) could be dissolved in weakly acid NaCl solutions. For late mineralization at $250^{\circ}C$, about $10^0$ to $10^{-1}\;ppm$ copper could be dissolved. Equilibrium thermodynamic interpretation indicates that the copper in the Haman-Gunbuk systems could have been transported as a chloride complex and the copper precipitation occurred as a result of cooling accompanied by changes in the geochemical environments ($fs_2$, $fo_2$, pH, etc.) resulting in decrease of solubility of copper chloride complexes.

키워드

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