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Crustal deformation and submarine canyon incision in a Meso-Cenozoic first-order transfer zone (SW Iberia, North Atlantic Ocean)

Sousa Lemos Pereira, Ricardo Nuno and Alves, Tiago Marcos 2013. Crustal deformation and submarine canyon incision in a Meso-Cenozoic first-order transfer zone (SW Iberia, North Atlantic Ocean). Tectonophysics 601 , pp. 148-162. 10.1016/j.tecto.2013.05.007

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Abstract

Using a dense grid of high-quality 2D seismic profiles, dredge and outcrop data, the offshore prolongation of a first-order transfer zone, the Messejana–Plasencia Fault Zone (MPFZ), is explained within the context of oblique rifting between Southwest Iberia, Newfoundland, and West Tethys. The offshore MPFZ is shown to comprise a 5–10 km wide region of deformation, oblique to the continental margin, reactivated in the Mesozoic as part of a wider transcurrent domain, the São Vicente sub-basin. Here, the geometry of faults and strata denotes the generation of a pull-apart basin during the Jurassic-Early Cretaceous. In contrast, its Late Cretaceous to Cenozoic evolution favours left-lateral transpression during the counter-clockwise rotation and eastward migration of Iberia towards its present position. Erosion was subsequently enhanced in the São Vicente sub-basin due to the reactivation of syn-rift structures. By documenting the evolution of the São Vicente sub-basin, and adjacent MPFZ, this work demonstrates: 1) the temporal and spatial scales in which first-order transfer zones accommodate crustal movements during continental rifting and subsequent inversion episodes; 2) the generation of an extensive region of strain accommodation in the vicinity of the MPFZ, an observation with profound implications to future palaeogeographic reconstructions of the North Atlantic Ocean; and 3) that the São Vicente Canyon, the physiographic expression of the MPFZ, incised the margin as early as the latest Cretaceous-Paleocene, synchronously with the onset of tectonic uplift in Southwest Iberia. In such a setting, the São Vicente sub-basin and MPFZ formed important by-pass corridors for sediment sourced from proximal areas of the margin. At present, the MPFZ comprises a complex releasing-restraining bend accommodating important vertical and horizontal movements in Southwest Iberia. Based on earthquake data from similar transfer zones, the MPFZ should be able to generate large-magnitude earthquakes and potentially destructive tsunamis.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: G Geography. Anthropology. Recreation > GC Oceanography
Uncontrolled Keywords: Divergent margins; Transfer zones; Tectonic inversion; Submarine canyon incision; North Atlantic; Geohazards
Publisher: Elsevier
ISSN: 0040-1951
Funders: Partex Oil and Gas
Last Modified: 04 Jun 2017 05:08
URI: http://orca.cf.ac.uk/id/eprint/48751

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