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Evidences of Pliocene-Quaternary and active tectonics on the Portimao Bank (Western Gulf of Cadiz margin)

AuthorsVázquez, J. T.; Alonso, Belén ; Ercilla, Gemma ; Estrada, Ferran ; García, Marga ; Juan, Carmen
Issue Date24-Sep-2013
PublisherRegional Committee on Atlantic Neogene Stratigraph
CitationV RCANS Congress Abstract Book: 44 (2013)
AbstractThe Portimao Bank is a structural high situated at the westernmost part of the Gulf of Cadiz continental margin, in the lower slope of the South Portuguese sector, between 3500 and 1200 m depth. This high has a W-E orientation and is bounded on the north by the D. Carlos valley and on the south by the Cadiz valley. This morphostructure has been related to a Variscan basement high strongly deformed by NW Africa-Eurasia convergence during Pliocene-Quaternary times and has been defined like a pop-up structure controlled by reverse faults both northwards and southwards with Pliocene-Quaternary activity. From a structural point of view, this bank exhibits a clear differentiation between western and eastern sectors. The main objective of this work is to contribute to the knowledge of the Pliocene-Quaternary and actual tectonic evolution of the Portimao Bank. This has been possible by the interpretation of the high resolution singled airguns and parametric profiles obtained in the MONTERA 0412 cruise, and two previous MCS profiles acquired in the TASYO 2000 cruise. Bank morphology shows a southern flank steeper and more gravity eroded than in the northern one, where also intense erosion is observed related to the D. Carlos valley. The summit shows a ramp-like morphology down westwards. However, this morphology is broken by the presence of the D. Carlos diapir in the center part of this bank, which marks also the boundary between western and eastern structural styles. In the eastern sector a basement high has been observed southwards which is interpreted as a reactivated reverse fault, which uplifted Pliocene-Quaternary units that thinning on the top. Northwards a longitudinal ridge is delimited at seafloor surface in relation to an anticline fold which is caused by a blind thrusts. In this sector the Pliocene-Quaternary uplift of the Portimao Bank is controlled by blind thrusts bounding the north and south. Their central part corresponds to an uplifted basin with syncline geometry and could be described as an inverted relief. Meanwhile, in the western sector the Pliocene-Quaternary units show a general antiform or tilted-southwards structure. In this area northern flank is related also to a blind thrusts whose activity show a major control on morphology. The recent and active deformation is observed along the northeastern sector of this high and significantly affects their morphology. In this way it is interpreted a marked deformation of actual sedimentary units by the diapirism activity probably related to D. Carlos diapir that causes a conical shape in the central part of the high. This recent deformation could be related to diapirism or reverse faults reactivation mainly along the north Portimao Bank sector
DescriptionVázquez, J. T. et al.-- V Regional Committee on Atlantic Neogene Stratigraphy (RCANS) Congress: Two decades of Atlantic Neogene study, 24-26 September 2013, Huelva. Más información en http://uhu.es/RCANS_Huelva/index.php?url=welcome.
Publisher version (URL)http://rabida.uhu.es/dspace/bitstream/handle/10272/7006/Two_decades_of_atlantic.pdf?sequence=2
Identifiersisbn: 978-84-695-8480-4
Appears in Collections:(ICM) Libros y partes de libros
(IACT) Libros y partes de libros
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