Current State and Future Prospect of Korean Activities on the Seafloor Sulfides and Cobalt-rich Crusts

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The Effect of Inorganic Salt on the Floatability of Galena and Pyrite

The objective of this study is to investigate the effect of inorganic salt on the floatability of sulfide minerals in freshwater (distilled water) and artificial seawater (0.6 M NaCl) using Hallimond tube. It was found that the addition of inorganic salt slightly increases the floatability of sulfide minerals under the conditions without using collectors, whereas adding inorganic salt decreases their flotation recovery a little under the conditions of using collectors such as xanthate. The effect of the addition of inorganic salt on the flotability of the sulfide minerals was not significant. It was concluded that, though seawater instead of freshwater is used as processing water, there is no significant effect on the floatability of sulfide minerals in the flotation system of sulfide minerals-xanthate. The natural floatability of galena was higher than that of pyrite independent of the concentration of inorganic salt in processing water. It was difficult to separate the particles of galena and pyrite by only controlling pH of the seawater with xanthate. 무기염이 황화광물의 부유도에 미치는 영향을 조사하고자 담수(증류수) 및 인공해수(0.6 M NaCl)를 이용하여 Hallimond tube 부선실험을 실시하였다. 포수제를 사용하지 않은 부선계에서는 무기염이 황화광물의 자연부유도를 약간 상승시킨 반면에 잔세이트 부선계에서는 반대로 무기염이 황화광물의 부유도를 약간 감소시켰다. 그러나 무기염에 의한 부유도의 차이는 크지 않았다. 따라서 황화광물-잔세이트 부선계에서 부선용수로 담수대신 해수를 사용하여도 황화광물의 부선효율에는 큰 영향이 없을 것으로 판단되었다. 한편, 방연석의 자연부유도는 부선용수 내에 무기염의 존재 여부에 상관없이 황철석의 자연부유도보다 높았다. 인공해수 내에서 티올계 포수제인 잔세이트를 사용할 경우에는 수용액의 pH 조절만으로는 방연석과 황철석을 효과적으로 부유선별하기 어려웠다22Nkc

A note on the majore marine-related legal system of the Pacific Island Nations

적도태평양 소도서국들의 법률체계 특성과 해양관련 주요 법제들을 분석 하였다. 향후 적도태펴양 소도서국들과 상생협력과 지속가능한 개발 목표를 포함한 전 지구적 해양문제 해결을 위한 정부정책 수행 그리고 민간자본과 기술의 진출에 대비해서 적도태평양 소도서국들의 관련 법제에 대한 사전 문석 필요성을 제기하였다. 분석결과, 적도태평양 도서국들의 법츌체계는 역사적 배경과 관습법적 전통과 혼재되어 있어, 매우 복잡한 체계를 보이고 있다. 한편, 해양관련 주요 법제 분석결과는 주로 유엔해양법협약을 국내적으로 수용하는 해양관할권 관련 법제가 대부분이며, 외국인 어업의 규제에 관한 법제, 해양환경보전에 관한 법제 그리고 해운.해사 관련 일부 법제 현황이 파악되었다.전반적으로 해양을 관리, 이용, 보전하기 위한 체계적 법률체계를 갖추지 못하고 있는 것으로 파악되었다.양 소도서국들의 관련 법제에 대한 사전 문석 필요성을 제기하였다. 분석결과, 적도태평양 도서국들의 법츌체계는 역사적 배경과 관습법적 전통과 혼재되어 있어, 매우 복잡한 체계를 보이고 있다. 한편, 해양관련 주요 법제 분석결과는 주로 유엔해양법협약을 국내적으로 수용하는 해양관할권 관련 법제가 대부분이며, 외국이 ㄴ어업의 규제에 관한 법제, 해양환경보전에 관한 법제 그리고 해운.해사 관련 일부 법제 현황이 파악되었다.전반적으로 해양을 관리, 이용, 보전하기 위한 체계적 법률체계를 갖추지 못하고 있는 것으로 파악되었다.22othe

Preliminary Feasibility Study for the Commercial Development of Seafloor Hydrothermal Deposits in the EEZ of the Kingdom of Tonga

Hydrothermal deposits on deep-sea floor are expected to be potential metal resources for the future demands. Recently, Korea was granted prospecting licences for the exclusive economic zone (EEZ) of the Kingdom of Tonga and is undertaking exploration for hydrothermal metal deposits on the deepsea floor. The Korean Deep Seabed Mining Group (KDSMG), which consists of four Korean companies involved in the marine technologies, oil and gas shipping, and smelter industries, has conducted research to evaluate the area's resource potential in cooperation with the Ministry of Land, Transport and Maritime Affairs (MLTM) of Korea.This paper presents results of a feasibility study for the commercial development of seafloor hydrothermal deposits, and some exploration results performed on Tonga Arc area with evidence for newly discovered hydrothermal vents.1

Mantle heterogeneity observed in MORB from the northern Central Indian Ridge, 8°-17° S

The northern Central Indian Ridge (CIR), between 8° and 17° S, composed of 7 segments of which spreading rates increase southward from ~35 mm/yr to ~40 mm/yr. Although composition of several rock samples from the northern CIR was included in early studies of 1970s, no systematic study of the northern CIR was reported yet. During the expeditions for hydrothermal activities in the northern CIR conducted by KORDI, the first detailed mapping and sampling of volcanic rocks along the ridge axis were performed. Major, trace element and Sr-Nd-Pb isotope compositions in basaltic glasses from spreading axis along the northern CIR reveal two distinct enriched mantle sources. In the southern segments, specifically for segments 6 and 7, lava samples generally show high Nb/Yb and 87Sr/86Sr and low 206Pb/204Pb. The enrichment pattern coincides with the Reunion plume composition as well as enriched lava collected from the southern CIR. Thus, the enriched mantle of the southern segments can be supplied from the Reunion hotspot plume (EM2) despite of the possible role of the Marie Celeste fracture zone as a compositional boundary. Another enriched source, characterized by high La/Sm and 206Pb/204Pb and low 87Sr/86Sr, is observed in lavas from the northern segments. This enriched source is compositionally distinct from the Reunion plume component and shows geochemical affinity with FOZO component. Our data possibly suggest the ubiquity ofFOZO-type component in the MORB-forming mantle. However, enrichment process for the formation of FOZO-type mantle should be investigated for further research.1

Magnetic anomaly analysis of two adjacent seamounts (Ita Mai Tai and OSM2) in the western Pacific

서태평양 마샬제도 북쪽에 위치하는 해저산 Ita Mai Tai(12° 50'N,156° 50'E)와 OSM2(130 55'N, 157° 35'E)에 대해 지자기 탐사를 실시하였다. 다중빔 음향측심기를 이용하여 정확한 해저지형 및 수 심자료를 획득하였고,해수면 근처에서 견인하는 Proton precession 자력계를 이용하여 총자기장을 획 득하였다. Plouff (1976)가 제시한 최소자승 알고리즘을 이용하여 해저산의 자기변수를 계산하였고 이 로부터 해저산의 생성당시 고지자기 극을 추정하였다. 지자기 이상이 해저산의 생성당시 잔류자기만 으로 형성되었다고 가정할 때,Ita Mai Tai의 생성당시 복각 및 편각은 각각 -53.20, 25.0°이고,OSM2 는 각각 -26.1°,13.0°이다. 이로부터 구한 두 해저산의 생성당시 고지자기 극의 위치는 각각(490 2TW, 37° 38'N) 과 (47° 53'W, 59° 29'N) 이다. 두 해저산은 비쌍극자장이나 해저산의 생성과정에서 발 생한 지자기 역전 등에 의해 불균질화되어 낮은 적합도 비율을 보인다. 기존 연구에서 제시한 시대별 고지자기 극의 위치와 본 연구에서 구한 고지자기 극의 위치를 비교할 때,OSM2는 91 Ma의 고지자 기극과 일치하는 반면 Ita Mai Tai는 큰 오차를 보인다. Total magnetic field measurements were collected over two adjacent seamounts in the western Pacific, the Ita Mai Tai (12° 50'N, 156° 50rE) and OSM2 (13° 55'N, 157° 35'E), as a part of manganese crust survey in June, 2000 onboard R/V Onnuri. High-resolution multibeam bathymetric data and total magnetic field near the sea surface were obtained for both seamounts. The magnetic anomaly data were inverted for best-fitting, least-squares, uniform magnetization based on the method of Plouff (1976), and the paleomagnetic poles were estimated. Assuming that the anomaly was caused by remanent magnetization, the inclination and declination of Ita Mai Tai are -53.2°, 25.0°, respectively, and those of OSM2 are -26.1°, 13.0°, respectively. The corresponding paleomagnetic poles for Ita Mai Tai and OSM2 are (49° 27rW, 37° 38'N) and (47° 537W, 59° 29'N), respectively. In general, the seamounts exhibit low goodness of fit ratios with large residual anomalies. This is attributed to varying long-term non-dipole magnetic field and inhomogeneity in magnetization of the seamounts.22Nkc

Comparison of Vane-shear Strength Measured by Different Methods in Deep-sea Sediments from KODOS area, NE Equatorial Pacific

북동태평양 심해저 생물자원 퇴적물에서 서로 다른 두 종류의 측정기 그리고 선상 및 육상 실험실에서 획득한 베인전단강도(vane shear strength) 자료의 비교 연구를 위하여 다중주상시료 채취기(multiple corer)로 규질 및 탄산질 퇴적물 시료를 채취하였다. 전단강도는 2.0×2.0 cm의 베인( 90∘ four blade vane)이 장착된 수동베인측정기(hand-held vane apparatus, 수동베인) 그리고 회전식 점도계 (rotational viscometer)에 1.0×0.88 cm의 베인을 장착하여 구성한 전동베인 측정기(motorized shear vane system, 전동베인)로 측정되었다. 수동베인과 전동베인으로 측정된 전단강도 값들은 코어 깊이에 따라 증가하는 동일한 변화 양상을 보이며, 절대 값도 유의한 차이를 보이지 않는다. 그리고 선상에서 측정된 전단강도 값에 비하여 3개훨월후 실험실에서 동일 장비에 의해 측정한 값들 또한 큰 차를 나타내지 않는다. 한편, 실험실에서 전동베인으로 동일한 코어를 2~4회 반복 측정한 결과 동일한 깊이에서도 측정 지점(hole)에 따라 차이가 나타난다. 또한 한 정점 내에서 서로 다른 코어 시료중 전단강도 값은 상당한 차이를 보이는 경우도 있다. 이는 심해저 주상 퇴적물의 물리적 특성이 생물 교란 작용 등의 영향으로 국부적으로 다르기 때문에 나타난 결과로 판단된다. 즉 심해저 퇴적물의 전단강도는 선상에서 또는 3개월이 지난 후 실험실에서, 그리고 두 종류의 기기를 사용하여도 깊이에 따른 유의한 차이를 보이지 않고, 오히려 한 코어시료 내의 국부적 물성차이 또는 한 정점 내 지점별 물성차이에 의한 변화 폭이 더 크게 나타낸다. Siliceous and calcareous deep-sea core sediments were collected by a multiple corer from the KODOS (Korea Deep Ocean Study) area, northeast equatorial Pacific, to compare vane shear strengths measured by two different apparatuses and in different places of on-board and on-land laboratories. The apparatuses were 1) a hand-held vane with four blades of 2.0×2.0 cm, and 2) a motorized shear vane system with four blades of 1.0×0.88 attached on a rotational viscometer. Depth profiles of shear strengths of core samples determined by the apparatuses do not show any consistent difference. Also, there is no consistent difference between shear strength values measured on-board and on-land laboratories after storing the core samples for three months in a cold room by a motorized shear vane system. However, there are considerable differences between depth profiles of shear strengths measured at four different points (holes) of a core sample. Moreover, significant differences among the profiles of different tube samples from a multiple corer within a sampling station were observed. Heterogeneity in physical properties of each depth and sediment column, possibly due to bioturbation and bottom current flows, is likely responsible for the differences in the geotechnical properties.33Nkciothe

Phosphatization of the Seamount OSM2, Southwestern Pacific

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Variation of Arc Signature in Volcanic Lavas from the Southern Tonga-Lau Arc and Back-Arc System

In the southern area of the Lau basin, Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) form the longest back-arc spreading axis. Recent studies (e.g. [1] [2]) have suggested a model of mantle wedge having the transition at 20.6°S (~70 km from the arc) from hydrous domain in the southern part to less hydrous one in the northern area, which controls the ridge morphology and segmentation in these spreading centers.Here we present, new major, trace element data and isotopic compositions of lavas dredged from the spreading ridges, ELSC and VFR, and the adjacent submarine arc volcanos of Tofua Arc (20-23°S) to examine the suggested mantle wedge structure in geochemically. We attempt to characterize geochemical affinities within the arc and back-arc system by comparisons of the along-axial variations of ELSC and VFR with the adjacent arc lavas located along slab flow lines. The major element data show that the volcanic rocks are dominantly basaltic, while some of more felsic rocks are found in the arc volcanos. In spidergram, the arc lavas are more depleted in incompatible elements at the north (TA10 and 11) of the transition zone than at the southern arcs. All analyzedvolcanic lavas show no significant variation in elemental proxy for mantle fertility (e.g. La/Sm and Nb/Yb). Whereas, they show latitudinal variations in selected trace element ratios, representing subduction component (e.g. Ba/Nb and Ba/Th°S (~70 km from the arc) from hydrous domain in the southern part to less hydrous one in the northern area, which controls the ridge morphology and segmentation in these spreading centers.Here we present, new major, trace element data and isotopic compositions of lavas dredged from the spreading ridges, ELSC and VFR, and the adjacent submarine arc volcanos of Tofua Arc (20-23°S) to examine the suggested mantle wedge structure in geochemically. We attempt to characterize geochemical affinities within the arc and back-arc system by comparisons of the along-axial variations of ELSC and VFR with the adjacent arc lavas located along slab flow lines. The major element data show that the volcanic rocks are dominantly basaltic, while some of more felsic rocks are found in the arc volcanos. In spidergram, the arc lavas are more depleted in incompatible elements at the north (TA10 and 11) of the transition zone than at the southern arcs. All analyzedvolcanic lavas show no significant variation in elemental proxy for mantle fertility (e.g. La/Sm and Nb/Yb). Whereas, they show latitudinal variations in selected trace element ratios, representing subduction component (e.g. Ba/Nb and Ba/Th1

Hydrothermal plume along the northern Central Indian Ridge, 8°S - 17°S: Magmatic and tectonic control on hydrothermal activity at slow-spreading ridge

CTD/MAPR profiles collected on 118 vertical casts on the slow-spreading Central Indian Ridge (8°S&#8211 17°S) reveal that hydrothermal plumes were most commonly associated with the asymmetric ridge sections where ultramafic massifs formed along one ridge flank near ridge-transform intersections or nontransform offsets (NTOs). The combined plume incidence for axial and valley wall casts, ph=0.30, is consistent with the existing global trend. This agreement confirms that thelong-term magmatic budget of the CIR is the primary control on the spatial frequency of hydrothermal venting at this slow spreading ridge. Because plume frequency was higher along asymmetrical than symmetrical ridge sections, permeability likely controls where venting is expressed. The occurrence of hydrothermal plumes at six locations on the axial flanks indicates that such cooling can also produce vent sites far off axis, perhaps fed by fluids channeled along detachment faults.ed along one ridge flank near ridge-transform intersections or nontransform offsets (NTOs). The combined plume incidence for axial and valley wall casts, ph=0.30, is consistent with the existing global trend. This agreement confirms that thelong-term magmatic budget of the CIR is the primary control on the spatial frequency of hydrothermal venting at this slow spreading ridge. Because plume frequency was higher along asymmetrical than symmetrical ridge sections, permeability likely controls where venting is expressed. The occurrence of hydrothermal plumes at six locations on the axial flanks indicates that such cooling can also produce vent sites far off axis, perhaps fed by fluids channeled along detachment faults.1