심해예인 고해상도 수심 자료와 후방산란 강도 자료를 이용한 인도양 중앙해령 내 Ocean Core Complex 구조의 지형적 특성 분석

• Published in: Ocean and polar research 2020, 42(1), , pp.49-61
• Main Authors: 황규하, 김승섭, 손승규, 김종욱, 고영탁, Hwang, Gyuha, Kim, Seung-Sep, Son, Seung Kyu, Kim, Jonguk, Ko, Youngtak
• Format: Article
• Language: Korean
• Subjects: 해양학
• ISSN: 1598-141X; 2234-7313

We analyzed the morphological characteristics of OCC (Ocean Core Complexes) in the middle part of the Central Indian Ridge (MCIR) using high-resolution geophysical data recorded on the Deep-Tow SideScan Sonar IMI-30 system. In terms of slope-gradient variations calculated from the high-resolution bathymetry data, the normal faults formed by seafloor spreading were associated generally with slopes > 30° and resulted in high backscatter intensities, which reflect more topographic effects than acoustic medium variation. However, the areas associated with gentle slopes < 10° tend to show the backscatter intensities reflecting the acoustic characteristic of the medium. We show that the detachment faults exposing the OCCs were initiated with high-angle normal faults (58°) exhibiting outward and inward dips of a breakaway zone. In order to examine the spatial distribution of OCC structures, we characterized the transition from magmatic-dominant seafloor with abyssal hills to tectonic-dominant seafloor with OCC using the down-slope direction variation. The slope direction of the seafloor generally tends to be perpendicular to the ridge azimuth in the magmatic-dominant zone, whereas it becomes parallel to the given ridge azimuth near the OCC structures. Therefore, this spatial change of seafloor slope directions indicates that the formation of OCC structures is causally associated with the tectonic-dominant spreading rather than magmatic extension. These results also suggest that the topographical characteristics of seafloor spreading and OCC structures can be distinguished using high-resolution geophysical data. Thus, we propose that the high-resolution bathymetry and backscatter intensity data can help select potential areas of exploitation of hydrothermal deposits in MCIR effectively.