Magnetic and gravity profiles across the Alpha Cordillera and their relation to Arctic sea-floor spreading

Abstract

Magnetic profiles over the Alpha cordillera have anomalies of wavelength 5 to 30 km and amplitudes frequently exceeding 1000 gammas. Further, the profiles show a reasonable degree of mutual correlation and biaxial symmetry over the ridge crest. Finally, the profiles appear to correlate with those from the flanks of other well-documented ridges in the Greenland and Norwegian seas and can be matched with a sea-floor spreading model over the paleomagnetic time span of 40 to 60 m.y.b.p. From this evidence, as well as from newly presented gravity data and analysis of existing additional geophysical and geological information, it is concluded that the cordillera may have been a dormant mid-ocean ridge active at least between 40 and 60 m.y.b.p. If this hypothesis is correct, the spreading rate from the ridge axis was 1 cm/yr and ended abruptly 40 m.y. ago.