Gravity constraints on the deep structure of the Pyrenean belt along the ECORS profile

Torné, Montserrat; Cabissole, B. de; Bayer, R.; Casas, A.; Daignières, M.; Rivero, A.

doi:10.1016/0040-1951(89)90039-5

Cited by 53 publications

(44 citation statements)

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“…But the prominence of the North Pyrenean maxima is commonly attributed to discontinuous high-density (≥2900 Kg m -3 ) bodies at shallow depth. These have been interpreted either as thrust slices (made of lower crust or upper mantle material; Torné et al, 1989;Casas et al, 1997;Vacher and Souriau, 2001;Pedreira et a., 2007;Jammes et al, 2010b) tectonically emplaced onto the North Pyrenean basement, or as autochthonous upper mantle uprises (Wang et al, 2016). Another debatable point resides in the southward extension of lower crustal and Moho reflections in the adjacent ECORS-Arzacq profile.…”

Section: Significance Of High-density Bodies In the Crustmentioning

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: Significance Of High-density Bodies In the Crustmentioning

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 thick crustal root beneath the axial zone also provides an explanation for the pronounced negative Bouguer anomaly observed along most of the Pyrenean range, except in its eastern termination close to the Mediterranean Sea (Daignières et al 1982). The Labourd and Saint Gaudens positive anomalies have been attributed to the presence of dense materials at shallow levels , but their exact nature and geometry are still uncertain (Torné et al 1989;Casas et al 1997;Vacher & Souriau 2001).…”

Section: Introductionmentioning

confidence: 99%

The Pyrenean architecture as revealed by teleseismic P-to-S converted waves recorded along two dense transects

Chevrot¹,

Sylvander²,

Díaz³

et al. 2015

Geophysical Journal International

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S U M M A R YBetween 2011 and 2013, two dense transects were deployed across the central and western Pyrenees to get better constraints on the deep lithospheric architecture and discriminate the competing models of the structure and formation of the Pyrenees. Each transect recorded the regional and global seismicity during a period of approximately 1 yr. Here, we exploit the records of teleseismic compressional waves and of their conversions to shear waves on internal discontinuities in order to map lithospheric interfaces beneath the two transects. The migrated sections, obtained by performing common conversion point stacks, are in remarkable agreement with the results of the ECORS-Pyrenees and ECORS-Arzacq deep seismic surveys. However, the migrations of converted waves reveal new details of the deep lithospheric architecture that could not be seen with the active source experiments. The new images provide clear and definite evidence for the subduction of a thinned Iberian crust down to at least ∼70 km depth, a result that has important implications for the formation of the Pyrenees. The subduction of the Iberian lithosphere leads to reconsider the amount of convergence between Iberia and Europe during the Cenozoic. A recent regional P-wave tomography, relying on the data of the PYROPE and IBERARRAY temporary experiments, revealed the segmentation of lithospheric structures by inherited Hercynian NE-SW transfer faults that were reactivated during the Albian rifting. Our migration images are consistent with this model, and give further support to the idea that the Pyrenees were produced by the tectonic inversion of a segmented hyperextended rift that was buried by subduction beneath the European Plate.

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“…The independent available geophysical information is used to define the following parameter ranges: (1) Moho depth; (2) Vs in the crust (Vs B 4.1 km/s); (3) Vs in the mantle layers (4.0 km/s B Vs B 4.8 km/s); (4) the total thickness of the parameterised structure cannot be higher than 350 km (the maximal depth of relevant penetration of our data). The parameter's steps Payo (1976), Vidal et al (1998) A-8 (2.5, 40.5) Payo (1976), Giese et al (1982), Mauffret et al (1995), Vidal et al (1998) a-8 (2.5, 41.5) Gallart et al (1980), Torne et al (1989), Casas et al (1997), Rivero et al (2002) b-8 (2.5, 42.5) Gallart et al (1980), Daignieres et al (1981), Gallart et al (1981), Torne et al (1989), Casas et al (1997), Fernandez et al (1998), Gallart et al (2001), Nercessian et al (2001), Rivero et al (2002) c-8 (2.5, 43.5) Gallart et al (1980), Daignieres et al (1981), Torne et al (1989), Casas et al (1997), Rivero et al (2002) B-9 (1.5, 39.5) Payo (1976), Giese et al (1982), Mauffret et al (1995), Vidal et al (1998) A-9 (1.5, 40.5) Payo (1976), Giese et al (1982), Mauffret et al (1995), Vidal et al (1998) a-9 (1.5, 41.5) Gallart et al (1980), Torne et al (1989), Mauffret et al (1995), Casas et al (1997), Fernandez et al (1998), …”

Section: Methods and Datamentioning

confidence: 99%

“…This assumption about the crust model biases the results of the inversion for the upper mantle structure, as it is shown in detail by Pontevivo and Panza (2006). The bias is particularly relevant in heterogeneous regions, such as the study area where the thickness of the crust varies between about 12-20 km in the Valencia Trough zone (Payo 1976;Giese et al 1982;Mauffret et al 1995;Laske and Masters 1997;Vidal et al 1998;Bassin et al 2000;Vera 2004) to about 40-50 km in the Pyrenees Daignieres et al 1981;Roure et al 1989;Torne et al 1989;Casas et al 1997;Masters 1997, Vidal et al 1998;Bassin et al 2000;Rivero et al 2002;Vera 2004), and the water depth, in the Mediterranean Sea part of the study area, can reach, on average, 2 km (online data from NGDC 2003). Van der Meijde et al (2003) determined the velocity structure under several seismic stations in the Mediterranean region using the receiver function technique.…”

Section: Introductionmentioning

confidence: 90%

“…(1989),Casas et al (1997),Fernandez et al (1998),Rivero et al al. (1981),Gallart et al (1981),Torne et al (1989),Casas et al (1997),Fernandez et al (1998),Rivero et al DSS in the Alboran Sea (1978),Polyak et al (1996),Serrano et al (2003) E-13 (-2.5, 36.5) WG for DSS in the Alboran Sea (1978),Banda and Ansorge (1980),Barranco et al (1990),Banda et al (1993),,Polyak et al (1996),Tandon et al (1998) D-13 (-2.5, 37.5) WG for DSS in Spain(1977),Banda and Ansorge (1980),Banda et al (1993),Carbonell et al (1998),Chourac et al …”

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confidence: 95%

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The shear-wave velocity structure of the lithosphere–asthenosphere system in the Iberian area and surroundings

Raykova

Panza

2010

Rend. Fis. Acc. Lincei

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The S-wave velocity model, to the depth of 300 km for the Iberian area and surroundings, is obtained with the non-linear inversion of Rayleigh wave tomographic data in the period range from 5 to 150 s. The three-dimensional model of the region is assembled from 74 juxtaposed one-dimensional cellular structures, sized 1°9 1°, by means of a local smoothing optimisation. The S-wave velocity model shows the almost constant velocity (*4.40 km/s) in the upper mantle beneath the Iberian Massif, the welldeveloped low-velocity zones in the Valencia Trough and under northwest Africa, and specific features of the upper mantle layering in the zone of the Iberian range. The thickness of the crust varies between 25 and 35 km with exceptions in the zones of the Valencia Trough (11-18 km) and Pyrenees (35-45 km). Our Vs models are well correlated with the geological structure along Transmed I and evidence several features of the lithosphere-asthenosphere system in the Betic-Rif domain: quite distinct Iberian, Alboran and Meseta crustal domains; relatively thin, well-developed lithosphere under the Rif system; and clearly defined boundary between the upper and lower asthenosphere. The cellular velocity model of the Betics, where ultrapotassic lamproitic magmatism is observed, has features similar to those of other three areas in the western Mediterranean where ultrapotassic lamproitic magmatism of different age is observed. The crust and upper mantle models in these four areas can be correlated with the age of the magmatism and the local heat flow, and outline how, starting from a naturally quite undifferentiated mantle where magma genesis is currently in progress, the differentiation in lithosphere and asthenosphere can take place in time.

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Gravity constraints on the deep structure of the Pyrenean belt along the ECORS profile

Cited by 53 publications

References 10 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

The Pyrenean architecture as revealed by teleseismic P-to-S converted waves recorded along two dense transects

The shear-wave velocity structure of the lithosphere–asthenosphere system in the Iberian area and surroundings

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