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
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...
Published in: | Geophysical Journal International |
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Main Authors: | , |
Format: | Text |
Language: | English |
Published: |
Oxford University Press
1991
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Subjects: | |
Online Access: | http://gji.oxfordjournals.org/cgi/content/short/106/2/357 https://doi.org/10.1111/j.1365-246X.1991.tb03898.x |
Summary: | 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. |
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