Late Jurassic sedimentation and deformation in the west Iberia continental margin: insights from FMS data, ODP Leg 173

Abstract

In the Iberia Abyssal Plain, Ocean Drilling Program (ODP) Site 1065 drilled the top of a continental tilted block, penetrating a Middle to Late Jurassic probable pre-rift sedimentary unit. Borehole images of this unit were obtained by the Formation MicroScanner (FMS) logging tool, thus allowing the identification and 3D measurement of two block tilting phases. The last one is an eastward 15° tilt, probably related to the main Early Cretaceous rifting phase, and consistent with the tilted block image on seismic lines. The first tilt, previously unknown, is Late Jurassic in age. The block tilting is 15° to the southeast, and is not associated with any noticeable change in the depositional environment. Both tilting episodes induced sedimentary instabilities, leading to listric faults and slumps. FMS images also showed that the sediments originated from the north (Galicia Bank) during Late Jurassic times.