Axial magnetic anomaly amplitude along the Mid-Atlantic Ridge between 20 deg N and 40 deg N

• Published in: Journal of Geophysical Research 1998-10, Vol.103 (B10), p.24
• Main Authors: Ravilly, Morgane, Dyment, Jerome, Gente, Pascal, Thibaud, Remy
• Format: Article
• Language: English
• ISSN: 0148-0227

After reduction to correct for the topography, spreading rate, latitude, and lineation azimuth effects, axial magnetic anomalies amplitudes are compared with bathymetric, gravity, seismological, and geochemical data along a 2600-km-long section of the Mid-Atlantic Ridge axis between 20 and 40 deg N. Significant results are obtained at two different scales, a regional one (greater than 100 km) related to sublithospheric thermal perturbations such as those associated to hotspots and a local one (less than 100 km) related to ridge segmentation. At a regional scale, two longwavelength highs of the axial magnetic anomaly amplitudes are observed between 37.5 and 40 deg N and between 27 and 30 deg N. The first high, associated with marked bathymetric, gravity, geoid, seismic velocity, and geochemical anomalies, is related to the Azores hotspot and is interpreted as reflecting the existence of a thick and/or Fe-Ti enriched magnetic source layer. A second long-wavelength high centered at 28.5 deg N corresponds to a weaker bathymetric and gravity signature; it is associated with a large low seismic velocity anomaly and a marked intermediate-wavelength positive geoid high which suggest higher sublithospheric temperatures, deeper and more extensive partial melting, and a thicker and/or Fe-Ti enriched magnetic source layer. (Author)