Multi-Beam Echo Sounding survery in the guyot, Magellan seamounts distribution characteristics of Co-rich ferromangese crust

Abstract

Korea Institute of Ocean Science & Technology (KIOST) has carried out the survey to secure Co-rich ferromangese crust resource on Magellan Seamounts for last 3 years. Major elements for exploitation of Co-rich ferromangese crusts are to narrow down the high potential area where crust is thick and to screen the site where accessibility of miner is good. Here we report the results of Multi-Beam Echo Sounding (MBES) survey and discuss the distribution characteristics of ferromangnese crust. In MBES survey, Konsberg Simard EM 120 12 kHz Multi-Beam Echo Sounder were used. The surveyed seamounts could be categorized into two types based on the size of the summit of mount and acoustic backscattering intensity (ABS) over the area: Type 1 is characterized by > 300 km2 of summit size and bimodal distribution of ABS mode. Whereas type 2 is featured by less than 300 km2 of summit size with normal distribution of ABS mode. Of five mounts, 3 seamounts of type1 reveal a relatively low ABS in center part of guyot but high ABS in guyot rims. Deep Sea Camera (DSC) observation over the type 1 shows carbonate-bearing unsolidified sediments cover in the central part of Guyot but Mn-crust exposure along the peripheral guyot. These observation is indicative of that high ABS well match to distributions of ferromangese crust. Type 2 seamounts represent the high ABS with normal distribution mode and Mn-crust is mostly observed in the camerarow down the high potential area where crust is thick and to screen the site where accessibility of miner is good. Here we report the results of Multi-Beam Echo Sounding (MBES) survey and discuss the distribution characteristics of ferromangnese crust. In MBES survey, Konsberg Simard EM 120 12 kHz Multi-Beam Echo Sounder were used. The surveyed seamounts could be categorized into two types based on the size of the summit of mount and acoustic backscattering intensity (ABS) over the area: Type 1 is characterized by > 300 km2 of summit size and bimodal distribution of ABS mode. Whereas type 2 is featured by less than 300 km2 of summit size with normal distribution of ABS mode. Of five mounts, 3 seamounts of type1 reveal a relatively low ABS in center part of guyot but high ABS in guyot rims. Deep Sea Camera (DSC) observation over the type 1 shows carbonate-bearing unsolidified sediments cover in the central part of Guyot but Mn-crust exposure along the peripheral guyot. These observation is indicative of that high ABS well match to distributions of ferromangese crust. Type 2 seamounts represent the high ABS with normal distribution mode and Mn-crust is mostly observed in the camera