Crustal structure of the Madeira-Tore Rise, eastern North Atlantic--results of a DOBS wide-angle and normal incidence seismic experiment in the Josephine Seamount region

• Published in: Geophysical Journal International
• Main Authors: Peirce, C., Barton, P. J.
• Format: Text
• Language: English
• Published: Oxford University Press 1991
• Subjects: Articles; Josephine; Mid-Atlantic Ridge; North Atlantic
• Online Access: http://gji.oxfordjournals.org/cgi/content/short/106/2/357; https://doi.org/10.1111/j.1365-246X.1991.tb03898.x

During November-December 1988, an extensive geophysical data set was collected over the Josephine Seamount, which is located at the northeasterly end of the Madeira-Tore Rise in the eastern North Atlantic. The Josephine Seamount lies at the intersection of the Madeira-Tore Rise and Azores-Gibraltar Fracture Zone, the latter representing the Africa-Eurasia plate boundary in this part of the eastern North Atlantic. From this data set, a 275 km long explosive refraction line has been modelled together with wide-angle airgun profiles, seismic reflection and gravity data. The velocity-depth model shows that the crust either side of the Seamount is typically oceanic in character. However, beneath the Seamount there exists a region of anomalously high velocity and crustal thickening to a depth of about 17-18 km. Gravity modelling also suggests that the Josephine Seamount is compensated by a crustal root, and that the Josephine Seamount/Madeira-Tore Rise system is in local isostatic equilibrium. Calculations of the flexural rigidity and effective elastic thickness of the lithosphere in this region suggest that the Madeira-Tore Rise formed contemporaneously with the lithosphere on which it lies. This age of crustal loading is consistent with the proposal that the Madeira-Tore Rise is an aseismic ridge which formed at or near the Mid-Atlantic Ridge.