Marine Magnetic Study of Spreading Ridges in the North Fiji Basin

Abstract

The North Fiji Basin in the South Pacific is located in the convergence boundary between the Pacific Plate and the India-Australia Plate. We performed the marine magnetic and bathymetry survey of spreading ridges in the North Fiji Basin. Study areas are composed of three regions(two regions in Central Spreading Ridge:CSR(KF-1,KF-3) and one region in Triple Junction:TJ(KF-2)). The surface-tow magnetic survey was carried out in this study areas. Magnetic and bathymetry data were acquired using Overhouser Proton Magnetometer SeaSPY(Marine Magnetics corporation) and Multi-Beam Echo Sounder EM120(Kongsberg corporation), respectively. From the measured datasets, we conducted the data processing of seabed topography, magnetic anomaly, and magnetization inversion for finding hydrothermal deposits. Low magnetization anomalies of these study areas are located at the end zones of ridge outer slopes that can be expected to be hydrothermal deposits. On the other hand, the spreading ridges of the study areas showed general Central Anomaly Magnetization High:CAMH. We can be expected better results by comparing the other study like geology and geochemistry in this area. For the precise analysis of the deep spreading ridge, we need deep-tow magnetic surveys in the future.udy areas are composed of three regions(two regions in Central Spreading Ridge:CSR(KF-1,KF-3) and one region in Triple Junction:TJ(KF-2)). The surface-tow magnetic survey was carried out in this study areas. Magnetic and bathymetry data were acquired using Overhouser Proton Magnetometer SeaSPY(Marine Magnetics corporation) and Multi-Beam Echo Sounder EM120(Kongsberg corporation), respectively. From the measured datasets, we conducted the data processing of seabed topography, magnetic anomaly, and magnetization inversion for finding hydrothermal deposits. Low magnetization anomalies of these study areas are located at the end zones of ridge outer slopes that can be expected to be hydrothermal deposits. On the other hand, the spreading ridges of the study areas showed general Central Anomaly Magnetization High:CAMH. We can be expected better results by comparing the other study like geology and geochemistry in this area. For the precise analysis of the deep spreading ridge, we need deep-tow magnetic surveys in the future.