BIBLIOS

Document type
Book chapters


Title
Influence of Salt Diapirism on the Basin Architecture and Hydrocarbon Prospects of the Western Iberian Margin

Participants in the publication
Pena dos Reis, R. (Author)
Nuno Pimentel (Author)
IDL
Fainstein, R. (Author)
M. Reis (Author)
Rasmussen, B. (Author)

Summary
The continental edge of the Western Iberian Margin is marked by two contrasting basins, the mostly onshore Lusitanian Basin and the mostly deepwater Peniche Basin. These two rift basins were originated during the opening of the North Atlantic Ocean and have similar characteristics and are geographically separated by an elongated basement high that strikes quasiparallel to the Portuguese coastline. The basins evolved during the Mesozoic as part of the Iberia Peninsula. The petroleum geology history of the relatively unexplored Lusitanian Basin is reconstructed in this chapter through the detailed stratigraphic mapping of outcrop and legacy exploratory drilling. The lesser-known Peniche Basin, to the west of the bounding basement high, is part of the deepwater continental margin of Iberia; knowledge of this basin is derived from seismic stratigraphic comparisons with Lusitanian Basin.\\\\nThe Lusitanian Basin developed over a Paleozoic basement terrane amalgamated during the Variscan orogeny. Triassic rift siliciclastic infill was followed by thick Norian to Hettangian salt-rich clays deposited in continental and coastal evaporitic sabkhas, named the Dagorda Formation. Carbonate deposition was installed during the Early and Middle Jurassic with marine sediments of epicontinental ramp and platform environments. The late Jurassic characterizes a new rifting episode with the realignment of the old basement structuring and erosion of the basin rift shoulders. The Early Cretaceous sedimentation was marked by the break-up of the North Atlantic whereas the late Cretaceous marks the tectonic inversion of the basin and its continued deformation.\\\\n\\\\nSalt pillows deforming the Late Triassic Dagorda unit date back from Early to Mid-Jurassic, whereas Late Jurassic tectonics and basin inversion are contemporaneous with the rise of salt diapirs and the massive salt walls of the Lusitanian Basin. The salt rise occurred preferentially through Hercynian basement faults continuing unabated throughout the Cenozoic. The late Cretaceous piercing of some diapirs and intense deformation along the bodies of the buried and piercing salt domes are related to the Alpine compressive events. These deformations continued until recent times along the bodies of buried piercing salt diapirs and salt canopies related to the Alpine contraction.\\\\nPetroleum exploration is active in both basins with acreage award commitments that include state-of-the-art seismic survey imagery to be followed by exploratory drilling. Salt structuring shaped the basins' architecture, providing the basis for structural closures or stratigraphic terminations, which are paramount to all of the deepwater hydrocarbon prospects that involve the Triassic red-beds play, the lower Jurassic salt diapir play and the post salt upper Jurassic and Cretaceous turbidites play.

Editor(s)
Juan I. Soto, Joan F. Flinch and Gabor Tari


Institution
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DE LISBOA

Where published
Permo-Triassic Salt Provinces of Europe, North Africa and the Atlantic Margins

Publication Identifiers
ISBN - 9780128094174

Publisher
Elsevier



Document Identifiers
DOI - https://doi.org/10.1016/B978-0-12-809417-4.00015-X