Anomalous magnetic field ∆Ta in the equatorial Indian Ocean (survey at polygons)

Abstract

After a long break, during the 42nd cruise of R/V «Academic Boris Petrov» (2017), the Shirshov Institute of Oceanology RAS has resumed full-scale geophysical research in the Indian Ocean. Along with bathymetric and seismoacoustic surveys, the cruise resulted in more than 10 000 km of profiles obtained during the modular hydro-magnetic survey. The main works were performed in the eastern equatorial part of the Indian Ocean, on the Northern segment of the Ninety East Ridge and in the zone of intraplate deformations in the central basin. Special algorithms have been developed for interpreting magnetic anomalies in low latitudes. A number of local intense magnetic anomalies have been detected on the polygons, for which equivalent source models have been developed. These models characterize the associated geological features. Estimations of paleolatitudes for a number of sites in the northern part of the Ninety East Ridge indicate the possible development of superimposed volcanic-magmatic processes here, which are not directly related to the magmatism of the Kerguelen hotspot. The study of intraplate deformations showed that the magnetic layer goes much deeper than the limits of the standard magnetic layer model of the oceanic lithosphere, and the studied objects are probably associated with cooled magmatic chambers formed on the flanks of the spreading ridge.

Keywords

• indian ocean
• anomalous magnetic field
• tectonics
• intraplate deformation