Database of Marine Magnetic Anomalies in the Northeast Pacific, Atlantic, and Southeast Indian Oceans.

Abstract

We have compiled 3.5 million data of marine magnetic anomalies in four areas in the Northeast Pacific, Atlantic, and Southeast Indian Oceans and tried to produce an expansive database of marine magnetic anomalies. The boundaries of the study areas are 20°-60°N and 170°-105°W for the Northeast Pacific, 20°-60°N and 70°-5°W for the North Atlantic, 50°-25°S and 45°W-10°E for the South Atlantic, and 60°-30°S and 125°-145°E for the Southeast Indian Ocean. Marine magnetic anomalies were obtained from geomagnetic total intensity data using IGRF/DGRF. All the data of marine magnetic anomalies in those areas were reduced to a 5-minute regular grid using weighted average interpolation. The gridded data in the North-east Pacific and the North Atlantic provide quite remarkable resolution of magnetic anomaly lineations, fracture zones, and seamounts. Results in the South Atlantic and the Southeast Indian Ocean show a limit of the gridding procedure due to low data density. We can, however, see characteristic patterns of marine magnetic anomalies corresponding to major tectonic features in parts of the areas where the data density is comparatively high. This attempt to make a database of marine magnetic anomalies has succeeded at least in the Northeast Pacific and North Atlantic Oceans, because magnetic anomaly maps confirm that characteristic features of marine magnetic anomalies in these areas are well represented by the gridded data. We can easily compare the magnetic database with other database such as the database of topography (ETOPO5). As more cruise data are accumulated in areas which have lack of magnetic data, this magnetic database will be more useful, especially to analyze a global marine magnetic anomaly.