Masters Thesis defence by Carlos Francisco Castro Soto Reyes – Niels Bohr Institutet - Københavns Universitet

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Masters Thesis defence by Carlos Francisco Castro Soto Reyes

The crustal structure of the East Greenland Ridge derived from refraction/wide-angle reflection seismic data

The East Greenland Ridge is a NW-SE trending 250-km-long and 30-km-wide ridge that separates the Greenland Basin to the south from the Boreas Basin to the north. Bathymetric data indicate that the East Greenland Ridge is composed of two overstepping ridge segments, an outer segment which is seaward and an inner segment which is landward. Previous geophysical investigations suggest that the ridge is a continental sliver that was sheared off the continental margin during the opening of the NE Atlantic. This study investigates the crustal structure of the ridge and the surrounding basins by developing a P-wave velocity model from refraction/wide-angle reflection seismic data.

The P-wave model shows that 1) the velocity model for the Greenland Basin is compatible with oceanic crust; 2) the presence of a sedimentary layer with a velocity of ~4.4 km/s on the East Greenland Ridge and in the Boreas Basin suggest that the layer must be older than the age of the oceanic crust; 3) velocities of both segments of the East Greenland Ridge are compatible with continental crust; and 4) the velocity model in the Boreas Basin could be either extended continental crust or highly serpentinized mantle.

This study provides the first unequivocal data that confirm the presence of transitional crust in the Boreas Basin and on the continental affinity of the inner segment of the East Greenland Ridge, something that was only poorly resolved in previous studies.