자원환경지질 (Economic and Environmental Geology)

  • 제35권1호
  • /
  • Pages.1-12
  • /
  • 2002
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  • 1225-7281(pISSN)
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  • 2288-7962(eISSN)
대한자원환경지질학회 (The Korean Society of Economic and Environmental Geology)
권호 표지

남서태평양 Manus Basin에서 산출되는 열수 분출구에 대한 지화학적 연구

Geochemistry of the Hydrothermal Chimneys in the Manus Basin, Southwestern Pacific Ocean

  • 이경용 (한국해양연구원 해양자원연구본부) ;
  • 최상훈 (충북대학교 지구환경과학과) ;
  • 박숭현 (한국해양연구원 해양자원연구본부)
  • 발행 : 2002.02.01
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초록

남서태평양 Manus Basin은 인도-호주판과 태평양판이 충돌하여 형성된 배호분지로 열수분출작용이 활발하며, 석영 안산암 및 현무암질 안산암 계열의 산성 화산암류를 기반암으로 발달한 열 수분출구 등 열수광체가 산재되어 있다. 열수분출구는 주로 황철석, 황동석, 백철석, 섬아연석, 방연석 등의 광석광불과 이에 수반되는 경석고, 중정석, 비정질 규소 등으로 구성되어 있으며, 황동석이 괴상으로 다량 산출되는 Cu-rich chimney와 섬아연석이 괴상으로 다량 산출되는 Zn-rich chimney로 대분된다. 열수분출구글 구성하는 금속원소들의 전체적인 상관관계에Ai Zn은 Sb, Cd, Ag, 등과 그리고 Cu는 Mo, Mn, Co 등과 좋은 정의 상관관계가 인지된다. 또한, 열수분출구에 따라 Zn-rich chimney에서는 Au가 Zn과 대단히 높은 정의 상관관계를 보여주며 Cd, Mn, Sb 등이 부화되어 있는 반면에, Cu-rich chimney에서는 Au가 Zn 및 Pb와 좋은 정의 상관관계를 보여주며 Mo, Co 등이 부화되어 있는 특성을 보여준다. 연구지역 Cu-rich chimney 및 Zn-rich chimney의 Au 평균품위는 각각 15.9 ppm 및 29.0 ppm이며, Ag, Cu, Zn 등 유용금속도 상당량 부화되어 있어 경제성이 높은 것으로 평가된다. Zn-rich chimney에 산출하는 경석고 및 비정질규소의 유체포유물 균일화 온도 및 염농도는 174~22$0^{\circ}C$ 및 2.7~3.6 equiv, wt.% NaCl로. 섬아연석 등 광석광물의 주 광화 작용이 약 20$0^{\circ}C$를 전후한 범위에서 진행되었으며, 이때 산소분압은 $10^{40.8}$bar이하에서 $10^{39.5}$이상으로 황분압은 $10^{14.7}$bar이하에서 $10^{13.4}$이상으로 각각 증가 전이되는 것으로 추론된다. 한편, Cu-rich chimney는 Zn-rich chimney의 주 광화온도조건보다 높은 온도에서 광화작용이 진행되었을 것으로 판단된다.

Manus Basin, located in the equatorial western Pacific, is a back arc basin formed by collision between the IndoAustralian and the Pacific Plates. The basin is host to numerous hydrothermal vent fields and ore deposits. The basement rocks of the Manus Basin consist primarily of dacite and basaltic andesite. Some of the minerals that form the hydrothermal chimneys that were dredged on the Manus basin include pyrite, chalcopyrite, marcasite, sphalerite and galena. The chimneys can be classified into chalcopyrite dominant Cu-rich type and sphalerite dominant Zn-rich type. The concentration of Zn shows good positive correlation with that of Sb, Cd and Ag. The content of Cu, on the other hand, positively correlates with that of Mo, Mn and Co. For samples that were taken from Zn-rich chimney, a strong positive correlation is found between Au and Zn contents. The chimney also shows enrichments of Cd, Mn and Sb. On the other hand, the samples from Cu-rich chimney exhibit strong correlation among Au, Zn and Pb, and are enriched in Mo and Co concentration. Average contents of Au in Cu-rich and Znrich chimneys were 15.9 ppm and 29.0 ppm, respectively. Because of high concentration of Au with Ag and Cu, the ore deposit have high economic potential. Homogenization temperatures and salinities of fluid inclusions in anhydrite and amorphous silica from Zn-rich chimney are estimated to be l74-220$^{\circ}$C and 2.7-3.6 equiv. wt. % NaCI, respectively. These value suggest that ore forming processes were occurred at around 200$^{\circ}$C and that the oxygen fugacity changed from 2: 10$^{-39.5}$bar to -s: 10$^{-40.8}$bar and the sulfur fugacity from -s: 10$^{-14.7}$bar to 10$^{-13.4}$bar during the process. It appears that the temperature at which the ores formed on Cu-rich chimney was higher than that on Zn-rich chimney.

키워드

참고문헌

  1. 연구보고서,BSPE99758-00-1240-7 해저열수광화작용의 지화학적 연구 Ⅱ 한국해양연구소
  2. Economic Geology v.88 Actively forming polymetallic sulfide deposits associated with felsic volcanic rocks in the eastern Manus back-arc basin Binns, R.A.;Scott, S.D. https://doi.org/10.2113/gsecongeo.88.8.2226
  3. Abstract from the Society of Economic Geologists Neves Corvo Field Conference Modern Analogue of a Mineral Field: Sea-Floor Hydrothermal Activity Hosted by Felsic Volcanic Rocks in the Eastern Manus Basin, Papua New Guinea Binns, R.A;Scott, S.D.;Gemmel, J.B.
  4. J. Geophysical Research v.93 A time-series of vent fluid compositions from 21°NEPR(1979, 1981, 1985), and the Guaymas Basin Gulf of California(1982, 1985) Campbell, A.C.;Bowers, T.S.;Edmond, J.M https://doi.org/10.1029/JB093iB05p04537
  5. Nature v.335 Chemistry of hot springs on the Mid-Atlantic Ridge Campbell, A.C.;Palmer, M.R.;Klinkhammer, G.P.;Bowser, T.S.;Edmond, J.M.;Lawerence, J.R.;Casey, J.F.;Thompson, G.;Humphris, S.;Rona, P.;Karson, J.A. https://doi.org/10.1038/335514a0
  6. SIO Reference 87-14 Studies of methane and helium in hydrothermal vent plumes, spreading-axis basalts, and volcanic island lavas and gases in southwest Pacific marginal basins. Craig, H;Poreda, R.
  7. Geochim. Cosmochim. Acta v.58 Zinc, copper, and lead in mid-ocean ridge basalts and the source rock control on Zn/Pb in ocean-ridge hydrothermal deposits Doe, B.R. https://doi.org/10.1016/0016-7037(94)90006-X
  8. Am. Jour. Sci. v.271 The solubility of carbon dioxide above 100℃ in water and in sodium chloride solutions Ellis, A.J.;Golding, R.M.
  9. Economic Geology v.80 Volcanism and Metallogenesis of axial and off-axial structures on the East Pacific Rise near 13°N Hekinian, R.;Fouguet, Y. https://doi.org/10.2113/gsecongeo.80.2.221
  10. Seafloor Hydrothermal system v.115-157 Physical and chemical processes of seafloor mineralization at Mid-Ocean Ridges Hannington, M.D.;Jonasson, I.R;Herzig, P.M.;Petersen, S.;Humphris, S.E.(ed.);R.A. Zierenberg(ed.); L.S. Mullineaux(ed.);R.E. Thomson(ed.)
  11. A review. Ore Geology Review v.10 Polymetallic massive sulfides at the modern seafloor Herzig, P.M.;Hannington, M.D. https://doi.org/10.1016/0169-1368(95)00009-7
  12. American Association of Petroleum Geologists Memoir no.53 Hydrocarbon Potential and Gold Mineralization in the New Ireland Basin, Papua New Guinea. In Geology and Geophysics of Continental Margins Marlow, M.S.;Exon, N.F.;Dadisman S.V.;Watkins, J.S.(et al.)(ed.)
  13. Marine Geophysical Researches v.18 Backarc Spreading, Rifting, and Microplate Rotation, Between Transform Faults in the Manus Basin Martinez, F.;Taylor B. https://doi.org/10.1007/BF00286078
  14. Hydrothermal Process at Seafloor Spresding Centers Rona, P.A.;Bostrom, K.;Laubier, L.;Smith, K. L.
  15. Nature v.321 Black smokers, massive sulfides and vent biota at the Mid-Atlantic Ridge. Rona, P.A.;Klinkhammer, G.;Nelsen, T.A.;Trefry, J.H;Elderfield, H. https://doi.org/10.1038/321033a0
  16. J. Gephysical Research v.99 Trace metals in the hydrothermal solutions from Cleft segment on the southern Juan de Fuca Ridge. Trefry, J.H.;Butterfield, D.B.;Metz, S.;Massoth, G.J.;Trocine, R.P.;Feely, R.A. https://doi.org/10.1029/93JB02108
  17. Ann. Rev. Earth Planet. Sci. v.18 Seafloor hydrothermal activity: Black smocker chemistry and chimneys Von Damm, K.L. https://doi.org/10.1146/annurev.ea.18.050190.001133
  18. Nature v.383 Possible contribution of a metal-rich magmatic fluid to a sea-floor hydrothermal system Yang, K.;Scott, S.D. https://doi.org/10.1038/383420a0