The Asturian Basin within the North Iberian margin (Bay of Biscay): seismic characterisation of its geometry and its Mesozoic and Cenozoic cover

Abstract

The distribution and structure of the Mesozoic and Cenozoic cover within the central part of the North Iberian Margin (Bay of Biscay) is analysed based on a dense set of 2D seismic reflection lines and logs. The integration of well data allows the recognition of seven seismostratigraphic units and the construction of a surface that illustrates the 3D morphology of this area at the time of the Jurassic rifting. The study zone comprises what is known as Le Danois Bank, a basement high, and the Asturian Basin, one of the sedimentary basins originated during the Iberian rifting at the end of the Paleozoic. Its development continued with the oceanisation of the Bay of Biscay as a failed arm of the Atlantic rift; later, during the Cenozoic, a drastic change in tectonic regime induced the partial closure of Biscay and building up the Cantabrian−Pyrenean chain along the northern border of Iberia. This compressional period left its imprint in the Asturian Basin sediments in the form of a mild inversion and general uplift. The geometry of the basin bottom appears as an asymmetric bowl thinning out towards the edges, with a main E‐W depocenter, separated by E‐W striking faults from a secondary one. Those bounding faults show twisted trends in the north, interpreted as a consequence of the compressional period, when a transfer zone in a N‐S direction formed between the two E‐W striking deformation fronts in Biscay. This study shows that the transfer zone extends further to the west, reaching the longitude of Le Danois Bank. The maximum thickness of the filling within the Asturian Basin is estimated in more than 10 km, deeper than assessed in previous studies. The recognition of frequent halokynetic structures at this longitude is another observation worth to remark. Based on this study, it is suggested that the basin formed on top of a distal basement block of stretched crust limiting with the hyperextended rifted domain of Biscay. This location largely conditioned its deformation during the late compression.

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

“…3D), of unresolved internal structure (Pedreira et al, 2015). Gallastegui, 2000;Cadenas andFernández-Viejo, 2016 andRoca et al, 2011). M: Moho discontinuity.…”

“…8) (Fig. 17A) (Cadenas and Fernández-Viejo, 2016). The Le Danois bank is a bathymetric promontory near the shelf break which coincides with a basement high, covered discontinuously by a thin Mesozoic-Tertiary succession (Boillot et al, 1979).…”

“…1). Descriptions and references of the upper crustal structure can be found in Alonso et al (1996), Gallastegui (2000) and Cadenas and Fernández-Viejo (2016). Previous crustal models have been proposed by Pulgar et al (1996), Fernández-Viejo et al (1998, 2000 Gallastegui (2000) and Pedreira et al (2003Pedreira et al ( , 2015, and are synthesized in Fig.…”

Constraints Imposed by Rift Inheritance on the Compressional Reactivation of a Hyperextended Margin: Mapping Rift Domains in the North Iberian Margin and in the Cantabrian Mountains

“…Following the Permo‐Triassic rift, a period of thermal subsidence affected the northern Iberian rifts during the Lower and the Middle Jurassic, leading to a general transgression and the development of characteristic marine facies that are progressively younger from west to east (González‐Fernández et al, ; Quintana, ; Riaza, ). These sediments, including dolomites, limestones, and calcareous claystones, have been interpreted as part of the pre‐rift units imaged in the Basque‐Cantabrian Basin and in the Asturian Basin (e.g., Cadenas & Fernández‐Viejo, ; Espina, ).…”

Formation of the Iberian‐European Convergent Plate Boundary Fault and Its Effect on Intraplate Deformation in Central Europe

“…East of approximately 7°W, plate convergence was accommodated by underthrusting Iberia beneath the North Iberian Margin, which was associated with the inversion of the Basque-Cantabrian Basin and the uplift of the Cantabrian Mountains (Diaz et al, 2016;Pedreira et al, 2003Pedreira et al, , 2007Roca et al, 2011;Ruiz et al, 2017). At the same time, the North Iberian Margin experienced shortening, which is documented by thrust faulting and reactivation of rift-inherited faults preferentially within the distal parts of the margin (Alvarez-Marron et al, 1997;Cadenas & Fernández-Viejo, 2016;Fernández-Viejo et al, 2012;Gallastegui et al, 2002;Tugend et al, 2014). The shortening along the North Iberian Margin has been interpreted to record limited southward subduction of the Bay of Biscay lithosphere beneath the North Iberian Margin, although this hypothesis remains poorly constrained and disputed (Alvarez-Marron et al, 1997;Fernández-Viejo et al, 2012;Gallastegui et al, 2002;Pedreira et al, 2015;Roca et al, 2011;Teixell et al, 2018).…”