PRELIMINARY-RESULTS OF NAUTILE DIVES ON T HE GORRINGE BANK (WEST PORTUGAL)

The oceanic crust exposed on the Gorringe Bank (SW Portugal) presents a lacolith-like body of gabbros, 500 m thick by 50 km long, within man tle peridotites. It also shows rare tholeiitic dikes and pillow-lavas resting locally directly over the peridotite. Gabbros, that crystalliz ed in a closed system, subsequently underwent strong deformation in hi gh- to low-temperature conditions, in a west to east extensional flat shear zone system. This massif would likely be formed during the early stages of oceanic spreading, at the end of continental rifting. This is an agreement with kinematic reconstructions for the North Atlantic Ocean. (C) Academie des sciences/Elsever, Paris.