Initial Reports of the Deep Sea Drilling Project - Volume 47 Part 2

This volume covers Leg 47, Part 2 of the cruises of the Drilling Vessel Glomar Challenger. On Leg 47B, the Glomar Challenger sailed from Vigo, Spain to Brest, France between April and May of 1976. Site 398 was drilled during Leg 47B of the Deep Sea Drilling Project 20 km south of Vigo Seamount which is on the southern end of the Galicia Banks on the western Iberian continental margin. Galicia Bank had the topographic appearance of a detached and isolated fragment of the Iberian Peninsula cut off from the mainland of Europe by a rather deep (-3000 m) trough. The location of Site 398 is within the axis of this trough approximately 160 km from the present-day coast of Portugal and immediately to the south of a major prominence known as Vigo Seamount. The JOIDES Passive Margin Advisory Panel considered the Galicia region as belonging to the continental margin province of the eastern North Atlantic. The attractiveness of the Galicia region for deep drilling in IPOD Phase I focused on the general absence of major offshore deltas (ancient and modern) along the western coast of Portugal, and hence, the likelihood of encountering a thinner blanket of Mesozoic and Cenozoic clastic sediments than exists on segments of the northwest African margin. From the earliest planning stage of IPOD Phase I, the location of Site 398 showed promise of permitting penetration with existing drilling technology into ancient marine sediments deposited on and transgressive across a continental edge during the rupture of southern Europe from North America.