TECTONIC SETTING OF AN INTRAOCEANIC RIDGE AT A CONVERGING PLATE BOUNDARY - THE GORRINGE BANK (OFF SW IBERIA)

Interpretation of a deep seismic reflection profile (IAM GB2) extendin g through the SW termination of the Gorringe Bank provides new structu ral and timing constraints regarding the emplacement of the ridge. Usi ng lateral variations of sedimentary sequences as indicators for verti cal movements lends to the conclusion that the ridge initiated during Barremo-Aptian times, in a general extensional setting. During Tertiar y times, the northerly wedging-out of the Tortonian nappe along the so uthern flank of the oceanic ridge is a sign of progressive uplift of t he the Bank as a response to the compressional stress induced further south, close to the Africa-Europe converging plate boundary. In the ki nematic model proposed here, both the extensional and compressional st ages of the Gorringe Bank culmination are thought to be controlled by steep N70 degrees-oriented crustal-scale discontinuities.