Visualisation method for the broad distribution of seafloor ferromanganese deposits
Shiki Machida, Taichi Sato, Kazutaka Yasukawa, Kentaro Nakamura, Koichi Iijima, Tatsuo Nozaki and Yasuhiro Kato
The increasing global demand for industrially critical metals has driven the development of deep-sea mineral resources. In the past, acoustic exploration has been utilised as an efficient technique for investigating deep-sea mineral resources. However, a practical method applicable to a wide distribution of resources has not yet been established. We show that the acoustic backscatter intensity of the seafloor determined using a vessel-equipped multi-narrow beam echo sounder provides an inherent threshold that bounds different types of geology, e.g. barren pelagic sediment and dense ferromanganese nodules. We found that multiple datasets from different sounders and/or the observation periods could be integrated on the basis of the thresholds that indicate the same geological boundaries. Furthermore, the integrated data and threshold provided visualisation and quantitative estimations regarding the distribution of ferromanganese deposits covering thousands of square kilometres. Our method is applicable after minimal data processing and ground-truth observations, and provides expeditious and exhaustive reconnaissance exploration.
Marine Georesources & Geotechnology: https://www.tandfonline.com/doi/full/10.1080/1064119X.2019.1696432