Original Article

Econ. Environ. Geol. 2016; 49(2): 121-134

Published online April 30, 2016

https://doi.org/10.9719/EEG.2016.49.2.121

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

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

Jongmin Joo1,2, Jonguk Kim1*, Youngtak Ko1, Seung-Sep Kim3, Juwon Son1, Sang Joon Pak1, Dong-Jin Ham1 and Seung Kyu Son1

1Deep-sea and Seabed Resources Research Division, KIOST, Ansan 15627, Korea
2Department of Marine Science and Covergent Technology, Hanyang University, Ansan 15588, Korea
3Department of Geology and Earth Environmental Sciences, Chungnam National University, Daejeon, 34134, Korea

Correspondence to : jukim@kiost.ac.kr

Received: January 13, 2016; Revised: March 25, 2016; Accepted: April 15, 2016

Abstract

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°. 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.

Keywords ferromanganese crust, seamount, acoustic survey, acoustic backscatter, seafloor video observation

서태평양 해저산의 망간각 자원평가를 위한 해저지형 특성 분석

주종민1,2, 김종욱1*, 고영탁1, 김승섭3, 손주원1, 박상준1, 함동진1, 손승규1

1한국해양과학기술원 심해저광물자원연구센터, 2한양대학교 해양융합과학과, 3충남대학교 지질환경과학과

요 약

Article

Original Article

Econ. Environ. Geol. 2016; 49(2): 121-134

Published online April 30, 2016 https://doi.org/10.9719/EEG.2016.49.2.121

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

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

Jongmin Joo1,2, Jonguk Kim1*, Youngtak Ko1, Seung-Sep Kim3, Juwon Son1, Sang Joon Pak1, Dong-Jin Ham1 and Seung Kyu Son1

1Deep-sea and Seabed Resources Research Division, KIOST, Ansan 15627, Korea
2Department of Marine Science and Covergent Technology, Hanyang University, Ansan 15588, Korea
3Department of Geology and Earth Environmental Sciences, Chungnam National University, Daejeon, 34134, Korea

Correspondence to:jukim@kiost.ac.kr

Received: January 13, 2016; Revised: March 25, 2016; Accepted: April 15, 2016

Abstract

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°. 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.

Keywords ferromanganese crust, seamount, acoustic survey, acoustic backscatter, seafloor video observation

서태평양 해저산의 망간각 자원평가를 위한 해저지형 특성 분석

주종민1,2, 김종욱1*, 고영탁1, 김승섭3, 손주원1, 박상준1, 함동진1, 손승규1

1한국해양과학기술원 심해저광물자원연구센터, 2한양대학교 해양융합과학과, 3충남대학교 지질환경과학과

Received: January 13, 2016; Revised: March 25, 2016; Accepted: April 15, 2016

요 약

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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