Characteristics of Seafloor Morphology and Ferromanganese Nodule Occurrence in the Korea Deep-sea Environmental Study (KODES) Area, NE Equatorial Pacific

Abstract

SeaXoor morphology and ferromanganese nodule occurrence were studied using a multibeam side scan sonar (SeaBeam, 2000) and a deep-sea camera system in the Korea Deep-sea Environmental Study (KODES) area, northeast equatorial PaciWc. SeaXoor morphology and nodule abundance are highly variable even in this small study area. The NNE± SSW oriented hills are parallel and about 100± 200 m high. Valleys are very Xat-Xoored, while hilltops are rugged with depressions of tens of meters. CliVs to about 100 m bound the valleys and the hills. The study area can be classiWed into three types based both on nodule occurrence and seaXoor morphology, mostly G-and B-types and some M-type. G-type is characterized by high nodule abundance, ubiquitous bioturbation, and Xat seaXoor morphology, while B-type is characterized by irregular-shaped nodules, variable nodule abundance, occurrence of giant nodules and sediment lumps, rugged bottom morphology with depressions, and white calcareous surface sediments. Medium nodule abundance and a generally Xat seaXoor characterize M-type. G-type occurs mostly in the valley regions, while Btype is on the hilltop areas. M-type is located between the hilltop and the valley. Tectonic movement of the PaciWc plate resulted in the elongated abyssal hills and cliVs. The rugged morphology on hilltops resulted from erosion and redistribution of surface siliceous sediments on hilltops by bottom currents, outcropping of underlying calcareous sediments, and dissolution of the carbonate sediments by corrosive bottom water undersaturated with CaCO3. Sediment eroded from the hills, which is relatively young and organic-rich, is deposited in the valleys, and diagenetic metal 167

Understanding Mn-nodule distribution and evaluation of related deep-sea mining impacts using AUV-based hydroacoustic and optical data

“…Several studies correlate bathymetry and nodule occurrence, revealing a complex/non-coherent interrelation which mainly depends on the considered spatial scale. Most studies have focused on nodule occurrence variability between very different terrain settings such as seamounts, valleys, plains and undulating terrain (Halbach, 1988;Pattan and Kodagali, 1988;Skornyakova and Murdmaa, 1992;Sharma and Kodagali, 1993;Park et al, 1997;Jung et al, 2001;Kim et al, 2012). The detected Mn-nodule variability has been associated with sediment deposition properties, e.g., assuming increased accumulation of sediment in flat or depression areas compared to sloping seafloor (Frazer and Fisk, 1981;Widmann et al, 2014).…”

“…The detected Mn-nodule variability has been associated with sediment deposition properties, e.g., assuming increased accumulation of sediment in flat or depression areas compared to sloping seafloor (Frazer and Fisk, 1981;Widmann et al, 2014). Local sediment accumulation influences the dominant formation type of the Mn nodules (diagenetic vs. hydrogenetic), their size and metal concentration (Jung et al, 2001;Kim et al, 2012;Mewes et al, 2014;Widmann et al, 2014), but detailed small-scale investigations (1 to 100 m scale) are not commonly done. Okazaki and Tsune (2013) propose to perform such investigations to improve our knowledge about Mn-nodule formation processes and the affecting parameters.…”

Evaluation of Resuspended Sediments to Sinking Particles by Benthic Disturbance in the Clarion-Clipperton Nodule Fields

“…Korea Institute of Ocean Science & Technology (KIOST, formerly known as KORDI) has completed a number of studies in the manganese nodule fields of the CCZ since 1997, including examination of the abundance of manganese nodules, deep-sea environmental properties, and particle fluxes ( Figure 1) (Jeong et al 1996;Jung et al 2001;Hyun and Yang 2005;Kim et al 2010Kim et al , 2011Kim et al , 2012. In general, meteorological and hydrographic conditions at Station KOMO (Korea Ocean Research & Development Institute Long-term Monitoring Station: 10 30 0 N, 131 20 0 W; ca.…”

Understanding Mn-nodule distribution and related deep-sea mining impacts using AUV-based hydroacoustic sensing and optical observations

“…Several studies correlate bathymetry and nodule abundance, revealing a complex/non-coherent interrelation which mainly depends on the con-10 sidered spatial scale. Most studies have focused on nodule abundance variability between very different terrain settings such as seamounts, valleys, plains and undulating terrain Halbach (1988); Pattan and Kodagali (1988); Skornyakova and Murdmaa (1992); Sharma and Kodagali (1993); Park et al (1997); Jung et al (2001); Kim et al (2012). The detected Mn-nodule variability has been associated with sediment deposition properties, e.g.…”

“…assuming increased accumulation of sediment in flat or depression areas compared to sloping seafloor Frazer and Fisk (1981); Widmann et al (2014). Local sediment accumulation 15 influences the dominant formation type of the Mn-nodules (diagenetic vs. hydrogenetic), their size and metal concentration Jung et al (2001); Kim et al (2012); Mewes et al (2014); Widmann et al (2014). Detailed small-scale investigations (1m to 100m scale) are not commonly done.…”