자원환경지질 (Economic and Environmental Geology)

  • 제49권2호
  • /
  • Pages.121-134
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  • 2016
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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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서태평양 해저산의 망간각 자원평가를 위한 해저지형 특성 분석

Characterizing Geomorphological Properties of Western Pacific Seamounts for Cobalt-rich Ferromanganese Crust Resource Assessment

  • 주종민 (한국해양과학기술원 심해저광물자원연구센터) ;
  • 김종욱 (한국해양과학기술원 심해저광물자원연구센터) ;
  • 고영탁 (한국해양과학기술원 심해저광물자원연구센터) ;
  • 김승섭 (충남대학교 지질환경과학과) ;
  • 손주원 (한국해양과학기술원 심해저광물자원연구센터) ;
  • 박상준 (한국해양과학기술원 심해저광물자원연구센터) ;
  • 함동진 (한국해양과학기술원 심해저광물자원연구센터) ;
  • 손승규 (한국해양과학기술원 심해저광물자원연구센터)
  • Joo, Jongmin (Deep-sea and Seabed Resources Research Division, KIOST) ;
  • Kim, Jonguk (Deep-sea and Seabed Resources Research Division, KIOST) ;
  • Ko, Youngtak (Deep-sea and Seabed Resources Research Division, KIOST) ;
  • Kim, Seung-Sep (Department of Geology and Earth Environmental Sciences, Chungnam National University) ;
  • Son, Juwon (Deep-sea and Seabed Resources Research Division, KIOST) ;
  • Pak, Sang Joon (Deep-sea and Seabed Resources Research Division, KIOST) ;
  • Ham, Dong-Jin (Deep-sea and Seabed Resources Research Division, KIOST) ;
  • Son, Seung Kyu (Deep-sea and Seabed Resources Research Division, KIOST)
  • 투고 : 2016.01.13
  • 심사 : 2016.04.15
  • 발행 : 2016.04.28
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초록

서태평양 공해 해저산의 다중빔 음향측심자료와 해저면 영상관측 자료를 활용하여 해저산 정상부와 경사면에 피복된 망간각의 공간 분포 변화 양상을 파악하였다. 다중빔 음향측심기를 이용하여 구분된 해저산의 지형 특성은 정상부 면적의 약 70% 이상이 경사가 $5^{\circ}$ 미만으로 비교적 평평한 지대로 이루어져 있으나 후방산란강도는 해저면의 매질변화를 지시하는 이봉분포를 보였다. 이 이봉분포에서 -30 dB이상의 높은 최빈값은 경사면과 정사부 가장자리 지역에서 우세하였으며 -30 dB이하의 낮은 최빈값은 정상부 중앙지역에서 우세하였다. 해저면 표층의 영상자료와 후방산란 자료의 연관성을 분석한 결과, 정상부 중앙지역은 경사면에 비해 상대적으로 완만한 기울기와 미교결 퇴적물만 존재하여 후방산란이 낮게 나타난다. 반면, 정상부 가장자리 및 경사면은 퇴적물이 없어 기반암이 노출되거나 망간각이 피복되어 후방산란이 높게 나타남을 보여준다. 따라서 다중빔 음향측심조사를 통해 획득된 후방산란 자료와 해저면의 퇴적물 및 망간각 분포 사이의 상관관계가 높다는 것을 알 수 있다. 이 연구결과는 다중빔 음향측심조사를 통해 획득된 후방산란 자료를 활용하면 기요형태의 해저산에 피복된 망간각의 전체적인 분포 규모를 확인할 수 있음을 의미한다. 따라서 해저산 지역의 망간각 개발 유망구역을 선별하는데 후방산란 자료가 유용하게 활용될 수 있을 것이다.

We characterize the spatial distribution of Cobalt-rich ferromanganese crusts covering the summit and slopes of a seamount in the western Pacific, using acoustic backscatter from multibeam echo sounders (MBES) and seafloor video observation. Based on multibeam bathymetric data, we identify that ~70% of the summit area of this flattopped seamount has slope gradients less than $5^{\circ}$. The histogram of the backscatter intensity data shows a bi-modal distribution, indicating significant variations in seabed hardness. On the one hand, visual inspection of the seafloor using deep-sea camera data exhibits that the steep slope areas with high backscatter are mainly covered by manganese crusts. On the other hand, the visual analyses for the summit reveal that the summit areas with relatively low backscatter are covered by sediments. The other summit areas, however, exhibit high acoustic reflectivity due to coexistence of manganese crusts and sediments. Comparison between seafloor video images and acoustic backscatter intensity suggests that the central summit has relatively flat topography and low backscatter intensity resulting from unconsolidated sediments. In addition, the rim of the summit and the slopes are of high acoustic reflectivity because of manganese crusts and/or bedrock outcrops with little sediments. Therefore, we find a strong correlation between the acoustic backscatter data acquired from sea-surface multibeam survey and the spatial distribution of sediments and manganese crusts. We propose that analyzing acoustic backscatter can be one of practical methods to select optimal minable areas of the ferromanganese crusts from seamounts for future mining.

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피인용 문헌

  1. An integrated method for the quantitative evaluation of mineral resources of cobalt-rich crusts on seamounts vol.84, 2017, https://doi.org/10.1016/j.oregeorev.2017.01.011