Abstract:
Data from several DSDP/ODP-Legs, submersible dives and dredge holes contributed to the knowledge of the general sedimentary development of the northern part of the western Iberian Margin (Galicia Bank, Iberian Abyssal Plain). Most recent data on the Upper Jurassic to Lower Tertiary sedimentary succession were collected during ODP-Leg 173. These results record the development of the margin from the pre-rifting shallow-marine shelf state in the Tithonian, the clastic rifting deposits related to the tilting of the fault blocks developed by crustal thinning, and the fi rst calcareous marine sediments of the Lower Cretaceous which were followed by Cretaceous to early Tertiary deep-marine clays and turbidites. Nearly continuous subsidence characterises this margin until the upper Miocene. A comparison of a simplifi ed Leg 173 sedimentary sequence with other Iberian margin successions (Lusitanian Basin, Ortegal Spur, Basque-Cantabrian Basin, Pyrenees, Iberian Chain, Betic Cordillera) shows that most facies similarities exist with the Subbetic sediment series of the central Betic Cordillera. In spite of large differences in bio- and lithofacies in other areas, synchronous tectonic events make it possible to correlate tectono-sedimentary sequences around Iberia. The major tectonic events recognisable in nearly all areas are the rifting phase in the late Jurassic (except in the Betic Cordillera), the break-up of the North Atlantic ("break-up unconformity") in the upper Early Cretaceous and the Eurasian Iberian plate collision in the late Eocene (Pyrenean orogenic phase, except in the Iberian Abyssal Plain). Two minor events are less time equivalent and restricted to the northern Iberian Plate (Galicia Bank to Iberian Chain) leading to several unconformities in the Turonian-Coniacian and Maastrichtian-Danian time intervals. The orogenic phase stopped the development at the southern, eastern and north-eastern margins, continuous sedimentation took place at the western and north-western margins.