The deep seismic reflection MARCONI-3 profile: Role of extensional Mesozoic structure during the Pyrenean contractional deformation at the eastern part of the Bay of Biscay

Abstract

a b s t r a c tThe new MARCONI-3 deep seismic profile allows recognition of the upper crustal structure of the eastern part of the Bay of Biscay and the main features of its Alpine geodynamic evolution. It denotes that the easternmost part of the Bay of Biscay consists of a thick wedge of uppermost Cretaceous to Cenozoic synorogenic sediments lying unconformably on the top of a thinned continental crust with the Mesozoic Parentis Basin to the north and the coeval Landes High to the south. The Parentis Basin appears as a major half-graben bounded southwards by a north-dipping planar fault. It is filled by a thick sequence of Jurassic-Upper Cretaceous carbonates affected by salt domes and squeezed diapirs made up of Triassic evaporites and mudstones. These salt tectonic structures also affect the overlying uppermost Cretaceous to Lower Miocene synorogenic deposits which are folded upon these structures. The Landes High includes a thin pre-Upper Cretaceous cover tilted to the south. In the Basque shelf, it is deformed by a basement-involving thrust wedge emplaced during the Late EoceneMiocene that constitutes the North-Pyrenean contractional front. Geometric relationships and thickness variations depict that this overall structure results from the following.

The role of salt layers in the hangingwall deformation of kinked-planar extensional faults: Insights from 3D analogue models and comparison with the Parentis Basin

“…This comparison allows to clarify the origin of the main structures and reinterpret the meaning of the intra-Albian unconformity previously labelled as the syn-rift/postrift boundary (Ferrer et al, 2008.…”

Crustal structure and evolution of the Pyrenean-Cantabrian belt: A review and new interpretations from recent concepts and data

“…1). The MARCONI profiles image the structure of the offshore sedimentary basins and intervening highs (Ferrer et al, 2008;Fernández-Viejo et al, 2011;Roca et al, 2011), but do not bring new key elements into the knowledge of the deep crust and Moho discontinuity. Coincident wide-angle/refraction data acquired with OBS and land stations are presented in Ruiz et al (2017), and largely coincide with earlier ESCIN wide-angle results.…”

Provenance of quartz-rich metamorphic tectonite pebbles from the “Black Flysch” (W Pyrenees, N Spain): An EBSD and detrital zircon LA–ICP-MS study

“…1A) record protracted syn-tectonic sedimentation inverted during the Paleogene (Cámara, 1997;Cuevas et al, 1999;Ferrer et al, 2008;Gómez et al, 2002;Martín Chivelet et al, 2002;Roca et al, 2011;Vergés and García Senz, 2001). A thick complex of siliciclastic or limy turbidites and pelagic deposits of Albian to early Eocene age (Barnolas and Pujalte, 2004) crops out in the most intensely deformed portion of the Basin, the so-called Basque Arc (Feuillée and Rat, 1971).…”

“…The ECORS-Bay of Biscay (Bois et al, 1997) and the MARCONI-3 seismic profiles (Ferrer et al, 2008;Roca et al, 2011) image the geometry of this domain, including the relationships between the Paleozoic basement and its Meso-Cenozoic sedimentary fill along the transect currently occupied by (from N to S) the Parentis Basin, the Landes high and the Cantabrian shelf. The geological interpretations of the seismic profiles show in the Landes high a Variscan basement covered by thin discontinuous Albian deposits or by younger successions (Ferrer et al, 2008;Jammes et al, 2010;Roca et al, 2011). Structural interpretations depict extensional structures with faulted and tilted blocks sealed by early cretaceous depositional units (Jammes et al, 2010, their Figs.…”