Legacy Seismic and Gravity Data in the Vicinity of Great Meteor Seamount and Its Tectonic Implications

Abstract

The Great Meteor seamounts are located in the eastern Atlantic Ocean, about 750 km south of the Azores. Conjugate to the Corner seamounts in the western Atlantic Ocean, it has been suggested they formed at the same hotspot that generated the New England Seamount chain. However, isotopic data suggest the Great Meteor seamounts are genetically linked to the Azores rather than to the New England hotspot. To test this, we have used seismic, gravity and bathymetry data acquired onboard M/V Meteor in 1990 to reassess the crustal structure, elastic thickness, T_e, and tectonic setting of the seamounts. The most prominent is Great Meteor, the largest seamount in the Atlantic Ocean. We show that the guyot comprises a pelagic, limestone (2.0–4.5 km s⁻¹) and extrusive basaltic lava (5.0–6.0 km s⁻¹) drape that overlies a relatively high P-wave velocity (6.0–6.5 km s⁻¹) intrusive “core” of mafic and possibly ultramafic rocks. The seismic structure has been verified by gravity modeling assuming a Gardner and Nafe-Drake relationship between P-wave velocity and density. The best fit between the observed and calculated gravity anomaly based on a plate flexure model is for an elastic thickness, T_e, of ∼20 km which implies an edifice age of ∼43 Ma, assuming a 450°C controlling oceanic isotherm. While the edifice age is greater than the sample age (∼17 Ma), it explains the subsidence history of Great Meteor and is compatible with dynamic models of plume-ridge interactions that predict the Azores hotspot has migrated north during the Cenozoic.