마리아나 해구 근처 NW Rota-1과 Esmeralda Bank에서의 지형조사와 자력탐사를 이용한 열수분출대에 대한 연구

Abstract

For bathymetry mapping and magnetic survey, we utilized the hull-mounted multibeam echo sounder and the towed magnetometer on the KORDI (Korea Ocean Research & Development Institute) R/V Onnuri. The shape of NW Rota-1 is corn type and the depth of summit is about -500 m b.s.l. NW Rota-1 doesn’t show steep slope or large valley, but has irregular topographic features in the south-eastern part. It is supposed to be formed by other eruptions of magma on the middle of seamount. The shape of Esmeralda Bank is caldera type with opening in the western part. The summit is very shallow, about -50 m b.s.l. The western part of Esmeralda Bank is steeper and more topographic irregular than eastern part and showed the valley made by erosion or collapse. The magnetic anomaly patterns of NW Rota-1 and Esmeralda Bank show low anomalies over the north and high anomalies over the south. The magnetic anomalies are steep over the summits and gently smooth over the deep bottom. The high anomalous zones of the analytic signals in the two survey areas are located at the summit of NW Rota-1 and at the summit and its western part in Esmeralda Bank. The low magnetization zone occurs over the summit of NW Rota-1 and is surrounded by the high zones correlated with its crater. The two low magnetization zones occur at the summit and the western part of Esmeralda Bank. The low magnetization zones suggest the possible existence of hydrothermal vents.