자원환경지질 (Economic and Environmental Geology)

  • 제50권6호
  • /
  • Pages.423-433
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  • 2017
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  • 1225-7281(pISSN)
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  • 2288-7962(eISSN)
대한자원환경지질학회 (The Korean Society of Economic and Environmental Geology)
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미얀마 깔레이미요 크롬철석광상 탐사의 지구화학적 인자

A Geochemical Indicator in Exploration for the Kalaymyo Chromitite Deposit, Myanmar

  • 박정우 (서울대학교 자연과학대학 지구환경과학부) ;
  • 박규승 (서울대학교 자연과학대학 지구환경과학부) ;
  • 허철호 (한국지질자원연구원 광물자원연구본부 자원탐사개발연구센터) ;
  • 김지혁 (서울대학교 자연과학대학 지구환경과학부)
  • Park, Jung-Woo (School of Earth and Environmental Sciences, Seoul National University) ;
  • Park, Gyuseung (School of Earth and Environmental Sciences, Seoul National University) ;
  • Heo, Chul-Ho (Mineral Resources Development Research Center, Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Kim, Jihyuk (School of Earth and Environmental Sciences, Seoul National University)
  • 투고 : 2017.11.28
  • 심사 : 2017.12.26
  • 발행 : 2017.12.28
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초록

한국지질자원연구원(KIGAM)과 미얀마 지질조사광물탐사국(DGSE)은 2013년부터 미얀마 깔레이미요지역 크롬광화대에 대한 공동 탐사를 진행하고 있다. 향후 효율적인 광물자원 예측 및 지질모델링을 위해서 지구화학 인자의 도출이 필요하다. 이 지역에 산출하는 크롬광체는 맨틀 고치형 크롬철석암이며 맨틀-용융체 상호반응으로 형성되는 것으로 알려져 있다. 따라서 크롬철석암을 중심으로 산출하는 하즈버가이트에 서로 다른 정도의 맨틀-용융체 상호반응의 결과가 관찰될 것으로 예상된다. 본 연구에서는 깔레이미요 크롬광화대에서 산출하는 암석의 첨정석에 대한 지구화학 분석을 실시하고 첨정석의 조성과 크롬철석암의 공간적 상관관계를 테스트하였다. 결과는 광체의 주변부에서 하즈버가이트의 첨정석 Cr#(molar Cr/(Cr+Al)${\times}$100)가 높은 반면에 광체에서 멀어질수록 Cr#가 낮아지는 경향을 보인다. 첨정석의 산출 양상도 Cr#에 따라서 명확히 구분된다. 높은 Cr#(>30)을 보이는 첨정석은 대부분 자형 또는 반자형이며 감람석에 둘러싸여 산출되는 반면 Cr#가 낮은 첨정석(<25)은 열편상 또는 타형으로 휘석의 경계부에 산출된다. 이 같은 암석학적, 지구화학적 분석결과는 모암인 하즈버가이트와 이를 침투한 용융체의 상호반응의 결과로 해석된다. 깔레이미요 지역의 크롬광체가 렌즈상 더나이트에 포획되어 산출하기 때문에 지금까지는 탐사의 지시 암석으로 더나이트를 활용하였으나 지표에 노출된 더나이트의 분포는 제한적이기 때문에 하즈버가이트 첨정석의 Cr#를 지화학적 지시자로 활용하여 향후 신규 탐사지역의 광화대 탐사 및 3D 지질 모델링에 적용할 수 있을 것이다.

Korea Institute of Geoscience and Mineral Resources and Department of Geological Survey and Mineral Exploration in Myanmar have explored the Kalaymyo chromitite deposit, Myanmar since 2013. It is now necessary to find a geochemical indicator for efficient mineral exploration in the future and building a 3D geological model for this ore deposit. Mantle podiform chromitite is a major type of Cr ore in this region, which is considered to be formed by mantle-melt interaction beneath the mantle-crust boundary of oceanic lithosphere. In this study we measured major element composition of spinels in harzburgite, dunite and chromitite, and examined the hypothesis that spinel Cr#(molar Cr/(Cr+Al)${\times}$100) can be used as a geochemical indicator in exploration for the Kalaymyo chromitite. The results show that there is a clear correlation between spinel Cr# and distribution of chromitite. The spinel Cr# of harzburgite increases with decreasing the distance from the chromitite bodies. The spinel composition is also closely associated with texture and occurrence of spinels. The high Cr# spinels (30-48) are subhedral to euhedral and enclosed by olivine whereas the low Cr# spinels (16-27) are anhedral and commonly associated with pyroxenes. Often the low Cr# spinels show symplectite intergrowths with pyroxenes, indicating their residual nature. These petrological and geochemical results suggest that the high Cr# spinels have resulted from mantle-melt interaction. We suggest that spinel Cr# can be used as a geochemical indicator for Cr ore exploration and as one of critical factors in 3D geological model in the Kalaymyo chromitite deposit.

키워드

참고문헌

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