AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin

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Geophysics definition of Peniche Basin, un-explored Atlantic Margin edge offshore Portugal


Peniche Basin developed in the Atlantic Margin offshore Portugal along the western edge of the Iberia peninsula. This un-explored basin has attracted interest due to its hydrocarbon potential. The basin formed as a rifted, non-volcanic, Atlantic continental margin type, trending on an N-S orientation that is roughly parallel to the Portuguese coastline between Lisbon and Aveiro. Its stratigraphy is genetically linked to the onshore Lusitanian Basin, these twin basins correspond to the inner (Lusitanian) and outer (Peniche) continental margin segments of West Iberia. This geophysics outlining of Peniche Basin ties its geology framework to the newly acquired geophysics data. Faults and fractures derived from the major tectonic events affecting the structuring of Peniche Basin may be identified on seismic, gravity and magnetics. Key reflectors representing the sedimentary deposition of siliciclastics and carbonates are clearly expressed on seismic records leading to the mapping of prospects above and beneath the original Triassic salt-rich unit, the Dagorda Fm. The Late Triassic rift is overlain by a Jurassic sag capped by a Callovian unconformity. Above it, the Late Jurassic/Early Cretaceous rift is filled by clastics progradation under the Late Aptian break-up unconformity as per drilling on the Lusitanian basin. Salt diapirs rose through fractures and shaped structuring of the Mesozoic sequences. These events and the structural fabric imprint from several episodes of tectonic inversions, Campanian, Late Eocene and Late Miocene, are identifiable on seismic leading to an overall comprehensive interpretation of structural geology and on the role of salt tectonics in the deepwater realm. Deepwater prospects are encountered at more than 1,500 meters of water depth, these are well defined structural anticlines with four-way dip closures shaped recently by late Miocene tectonic inversion of the basin Jurassic-Cretaceous depocenters, features recognized by geophysics data.