Annotated record of the detailed examination of Mn deposits from DSDP Leg 80 (Holes 548, 548A, 550, 551)

Deep Sea Drilling Project Leg 80 investigated the structural evolution and depositional history of the Goban Spur and the adjacent Porcupine Abyssal Plain. From the results of DSDP Leg 48, structural relationships and fossil assemblages indicated that the rifting of the Armorican margin created submarine relief of as much as 2000 m. Seafloor spreading began no later than the early Aptian and was accompanied by rapid crustal subsidence in the form of regional downwarping and tilting. Sites 548 to 551 were consequently placed along a transect across the continent/ocean boundary on the sediment-starved Goban Spur in order to further explore this particular structure.