The northwestern Iberian margin: A Cretaceous passive margin deformed during Eocene

Ocean-Continent Transition in the Iberia Abyssal Plain

“…Two phases of pre-breakup volcanism have been recognized by Ribeiro et al (1979) seamounts (Boillot et al, 1979). The Miocene deformation accompanied the formation of the Rif-Betic mountains and led to the gentle folding of sediments in the Iberia and northern Tagus abyssal plains, as apparent on reflection profiles (Masson et al, in press;Mauffret et al, 1989).…”

“…The northwestern edge of the deep Galicia margin (together with Galicia Bank) was uplifted during Cenozoic tectonic events, and the sedimentary cover was partly washed out by subsequent submarine erosion (Boillot et al, 1979;Grimaud et al, 1982;Mougenot et al, 1984). New seismic reflection data were obtained during a 1990 Lusigal cruise to map the S reflector and surrounding terranes northward, from the region where the S reflector is deeply buried, to the uplifted area where the sediment thins.…”

Composition of Lower Cretaceous Sandstone, Galicia Margin

“…A western source is not entirely excluded, however, because transport could have been through a break in or around a termination of the uplifted margin. Interpretation of a number of seismic profiles across Galicia Bank suggests that it may have been exposed during the Early Cretaceous, making it the most likely source for the sand (Boillot et al, 1979;Montadert et al, 1979;Winterer et al, 1986).…”

Galicia Margin

“…This implies that the locus of maximum thinning and rifting of the crust, where the first oceanic crust was later emplaced, was in a region that had been a structural high until the latest part of the Jurassic, and not in a region with a preceding history of rifting, subsidence and sedimentation. Cretaceous in age (Montadert et al, 1979;Boillot et al, 1979;1980;Groupe Galice, 1979;Mauffret and Montadert, in press). …”

“…Seismic and bathymetric studies, and dredge hauls, reveal many of the features considered typical of passive ocean margins (Montadert et al, 1974(Montadert et al, , 1979Groupe Galice, 1979;Boillot et al, 1979Boillot et al, , 1980Mauffret and Montadert, in press). Rift structures, apparent on seismic profiles, control the present-day morphology (Laughton et al, 1975;Vanney et al, 1979;Lallemand et al, 1985).…”