Seismic signature of Variscan and Alpine tectonics in NW Iberia: Crustal structure of the Cantabrian Mountains and Duero basin

Fernández‐Viejo, Gabriela; Muset, Josep Gallart; Pulgar, J. A.; Córdoba, Diego; Dañobeitia, Juan José

doi:10.1029/1999jb900321

Cited by 63 publications

(77 citation statements)

References 39 publications

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“…1) (Martín-González and Heredia, 2011). The crustal root thins out westward (Fernández-Viejo et al, 2000) and is no longer detected under the transfer fault zone, which shows a typical Variscan crust ca. 30 km thick (Téllez et al, 1993;Torné et al, 2015;Díaz et al, 2016) (see a map compilation of Moho thicknesses in Fig.…”

Section: Results Of the Escin Profiles Across The Cantabrian Mountainmentioning

confidence: 99%

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

et al. 2018

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International audienceThis paper provides a synthesis of current data and interpretations on the crustal structure of the Pyrenean-Cantabrian orogenic belt, and presents new tectonic models for representative transects. The Pyrenean orogeny lasted from Santonian (~84 Ma) to early Miocene times (~20 Ma), and consisted of a spatial and temporal succession of oceanic crust/exhumed mantle subduction, rift inversion and continental collision processes at the Iberia-Eurasia plate boundary. A good coverage by active-source (vertical-incidence and wide-angle reflection) and passive-source (receiver functions) seismic studies, coupled with surface data have led to a reasonable knowledge of the present-day crustal architecture of the Pyrenean-Cantabrian belt, although questions remain. Seismic imaging reveals a persistent structure, from the central Pyrenees to the central Cantabrian Mountains, consisting of a wedge of Eurasian lithosphere indented into the thicker Iberian plate, whose lower crust is detached and plunges northwards into the mantle. For the Pyrenees, a new scheme of relationships between the southern upper crustal thrust sheets and the Axial Zone is here proposed. For the Cantabrian belt, the depth reached by the N-dipping Iberian crust and the structure of the margin are also revised.The common occurrence of lherzolite bodies in the northern Pyrenees and the seismic velocity and potential field record of the Bay of Biscay indicate that the precursor of the Pyrenees was a hyperextended and strongly segmented rift system, where narrow domains of exhumed mantle separated the thinned Iberian and Eurasian continental margins since the Albian-Cenomanian. The exhumed mantle in the Pyrenean rift was largely covered by a Mesozoic sedimentary lid that had locally glided along detachments in Triassic evaporites. Continental margin collision in the Pyrenees was preceded by subduction of the exhumed mantle, accompanied by the pop-up thrust expulsion of the off-scraped sedimentary lid above. To the west, oceanic subduction of the Bay of Biscay under the North Iberian margin is supported by an upper plate thrust wedge, gravity and magnetic anomalies, and 3D inclined sub-crustal reflections. However, discrepancies remain for the location of continent-ocean transitions in the Bay of Biscay and for the extent of oceanic subduction. The plate-kinematic evolution during the Mesozoic, which involves issues as the timing and total amount of opening, as well as the role of strike-slip drift, is also under debate, discrepancies arising from first-order interpretations of the adjacent oceanic magnetic anomaly record

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Section: Results Of the Escin Profiles Across The Cantabrian Mountainmentioning

confidence: 99%

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

et al. 2018

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“…The profile provided the first seismic crustal image across the Cantabrian Mountains (Fig. 9a) Fernández-Viejo, 1997;Fernández-Viejo et al, 2000). The most outstanding feature of the profile is the S-N crustal structural variation.…”

Section: Seismic Modelling Resultsmentioning

confidence: 99%

“…This crustal thickening has also been imaged in other N-S wide-angle experiment located about 50 km to the west that extends northwards in the Cantabrian Margin Fernández-Viejo, 1997;Fernández-Viejo et al, 1998). Nearby E-W refraction profiles show that the crustal root trends E-W and disappears westwards in the continental margin (Fernández-Viejo, 1997;Fernández-Viejo et al, 2000) and extends eastwards under the Basque-Cantabrian basin in continuity with the Pyrenean crustal root (Pedreira et al, , 2007.…”

Section: Seismic Modelling Resultsmentioning

confidence: 99%

“…These later structures include (i) favourably oriented reworked Variscan thrusts and Mesozoic normal faults and (ii) newly formed faults Espina et al, 1996;Pulgar et al, 1999). Evidences of the Alpine deformation are also present further to the north in the North Iberian continental platform and abyssal plain, where north-verging thrusts developed, previous extensional Mesozoic faults were inverted, and the sedimentary cover was folded Gallastegui, 2000;Gallastegui et al, 2002;Fernández-Viejo et al, 2011. The present relief of the area is Alpine and its erosion supplied the detritus that filled the main synorogenic basins that developed in its boundaries: the inland Duero foreland basin in the south and the offshore Iberian Platform and abyssal plain basins in the north.…”

Section: Introductionmentioning

confidence: 99%

“…The ESCIN and MARCONI programs and other related projects were planned to study the deep crustal structure and evolution of the Cantabrian Mountains and continental margin from deep seismic reflection and refraction/wideangle data (Pérez-Estaún et al, 1994;Pulgar et al, 1995Álvarez-Marrón et al, 1996Álvarez-Marrón et al, , 1997Gallastegui et al, 1997;Ayarza et al, 1998;Fernández-Viejo et al, 1998, 2000Gallastegui, 2000;Gallastegui et al, 2002;Fernández-Viejo and Gallastegui, 2005;Fernández-Viejo et al, 2011. These studies showed that the deformation of the area due to the Alpine compression affected not only the shallow crustal levels but also the deeper ones.…”

Section: Introductionmentioning

confidence: 99%

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Alpine tectonic wedging and crustal delamination in the Cantabrian Mountains (NW Spain)

2016

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Abstract. The Cantabrian Mountains have been interpreted as a Paleozoic basement block uplifted during an Alpine deformation event that led to the partial closure of the Bay of Biscay and the building of the Pyrenean range in the Cenozoic. A detailed interpretation of deep seismic reflection profile ESCIN-2 and the two-dimensional seismic modelling of the data allowed us to construct a N–S geological cross section along the southern border of the Cantabrian Mountains and the transition to the Duero Cenozoic foreland basin, highlighting the Alpine structure. The proposed geological cross section has been constrained by all geophysical data available, including a 2-D gravity model constructed for this study as well as refraction and magnetotelluric models from previous studies. A set of south-vergent thrusts dipping 30 to 36° to the north, cut the upper crust with a ramp geometry and sole in the boundary with the middle crust. These thrusts are responsible for the uplift and the main Alpine deformation in the Cantabrian Mountains. A conspicuous reflective Moho shows that the crust thickens northwards from the Duero basin, where subhorizontal Moho is 32 km deep, to 47 km in the northernmost end of ESCIN-2, where Moho dips to the north beneath the Cantabrian Mountains. Further north, out of the profile, Moho reaches a maximum depth of 55 km, according to wide-angle/refraction data. ESCIN-2 indicates the presence of a tectonic wedge of the crust of the Cantabrian margin beneath the Cantabrian Mountains, which is indented from north to south into the delaminated Iberian crust, forcing its northward subduction.

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The seismogenic zone of the continental crust in Northwest Iberia and its relation to crustal structure

Llana‐Fúnez

Fernández

2015

Tectonics

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The distribution of seismicity at the western end of the Cantabrian mountain range (NW Iberia), reflecting current crustal dynamics, is investigated integrating seismically active structures, long-term structures, and the topographic features at the surface. The thickness of the seismogenic zone within the continental crust is established in 20 km. Two crustal domains can be distinguished in the study area in terms of the seismicity pattern, the style of Alpine structures and the relief. The presence of crustal fluids arises as a very likely contributing factor to the excessive thickness of the seismogenic zone in the study area. More importantly, a switch in tectonic style at the transition between crustal domains in coincidence with the lateral termination of orogenic frontal thrusts is envisaged as involving sufficient stress heterogeneity and amplification to explain the current concentration and characteristic pattern of historical seismicity in the region. Overall, the distribution of seismicity in the crust is sensitive to the type and style of crustal structures.

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Seismic signature of Variscan and Alpine tectonics in NW Iberia: Crustal structure of the Cantabrian Mountains and Duero basin

Cited by 63 publications

References 39 publications

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

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

Alpine tectonic wedging and crustal delamination in the Cantabrian Mountains (NW Spain)

The seismogenic zone of the continental crust in Northwest Iberia and its relation to crustal structure

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