2-D seismic modeling of the Variscan foreland thrust and fold belt crust in NW Spain from ESCIN-1 deep seismic reflection data

Gallastegui, J.; Pulgar, J. A.; Álvarez-Marrón, Joaquina

doi:10.1016/s0040-1951(96)00166-7

Cited by 26 publications

(29 citation statements)

References 17 publications

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“…We assume spatial and temporal point sources since our bandwidth is dominated by periods longer than 10 s. To take into account some important lateral variation of crustal parameters within the study area, three different models are used for different tectonic environments: (1) the Alboran Sea, and offshore conditions in general, (2) the Alpine mountain belts, and (3) the Hercynian basement and Mesozoic platforms. Initially, the models were derived by simplifying and averaging a selection of local and regional Earth models [e.g., Banda et al , 1993; Carbonell et al , 1998; Du et al , 1998; Gallastegui et al , 1997; ILIHA DSS Group , 1993; Téllez and Cordoba , 1998; Torné and Banda , 1992; J. Julià and J. Mejía, unpublished manuscript, 2002]. The models were optimized iteratively by trial and error, calculating Green's functions and inversions for a set of test events.…”

Section: Moment Tensor Inversionmentioning

confidence: 99%

Moment tensor solutions for small and moderate earthquakes in the Ibero‐Maghreb region

2003

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[1] We applied time domain moment tensor inversion of local and regional waveforms to small and moderate (M w = 3.5-5.7) shallow earthquakes from the Iberian Peninsula, northern Morocco, and northern Algeria. For the 6+ years period from November 1995 to March 2002 and the previous Network of Autonomously Recording Seismograms (NARS) experiment, moment tensor solutions were obtained for 58 events, considerably increasing the total number of available solutions in the study area. For each event we performed a moment tensor inversion and a double-couple grid search. For simple faulting events the grid search is valuable as a quality test for its ability to reveal potential ambiguities of the solutions and to assess confidence limits of fault plane parameters or principal axes orientation. The computed mechanisms show regional consistency: A large part of the Iberian Peninsula is characterized by normal faulting mechanisms with SW-NE oriented T axes. Thrusting and SE-NW compression is dominant in Algeria. In the Alboran Sea, the westernmost part of the Mediterranean, and the transition between both regimes, strike-slip mechanisms dominate with approximately N-S oriented P axes. This pattern suggests a regional anomaly characterized by clockwise rotation of the principal horizontal stress orientations.

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Section: Moment Tensor Inversionmentioning

confidence: 99%

Moment tensor solutions for small and moderate earthquakes in the Ibero‐Maghreb region

2003

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“…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%

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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“…5) because: 1.1When plotting the dip and thickness of the stratigraphic sequence, the detachment appears to be approximately at this depth. 2.1The interpretation of the regional-scale seismic profile ESCIN-1 by PØrez-Estan et al (1994, 1995 shows the basal thrust of the Aramo unit at 2.2 s (TWT) which, according to the seismic velocities used for this deep profile (4.5 km/s according to PØrez-Estan et al 1994; 5 km/s according to PØrez-Estan et al 1995;and 4.4±5.6 km/s according to Gallastegui et al 1997), is approximately equivalent to 4.9±5.5 km depth. 3.1The excess-area method derived by Chamberlin (1910) to calculate the detachment depth in cross sections involving folds has been applied to the cross sections illustrated in Fig.…”

Section: Geometry Of the Structuresmentioning

confidence: 99%

Internal structure and kinematics of Variscan thrust sheets in the valley of the Trubia River (Cantabrian Zone, NW Spain): regional tectonic implications

Bulnes

Marcos

2000

Int J Earth Sci

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The Variscan Belt in western Europe shows an arcuate geometry that is usually named Ibero-Armorican Arc. The nucleus of this arc, known as the Asturian Arc, comprises the Cantabrian Zone which is a foreland fold and thrust belt. The Trubia River area is located in the inflexion zone of the Asturian Arc, which is a strategic structural position for unraveling the geometry and kinematics of the Variscan thrust sheets and related folds. Geological mapping, construction of stratigraphic and structural cross sections, analysis of kinematic indicators, and estimate of shortening for each cross section have been carried out. This area consists of two major antiform±synform pairs related to two imbricate thrust systems. These folds are asymmetric, tight, and their axial traces follow the trend of the Asturian Arc. They have been interpreted as fault-propagation folds. The emplacement directions measured in the Trubia River area change from north to south and converge towards the core of the Asturian Arc. The minimum shortening estimated ranges between 16.4 and 17.6 km, which corresponds to 56.9 and 59.4%. The complex crosscutting relationships between folds and thrusts suggest that, in general, the different structural units followed a forward-breaking sequence of emplacement, with some breaching and a few out-of-sequence thrusts.

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2-D seismic modeling of the Variscan foreland thrust and fold belt crust in NW Spain from ESCIN-1 deep seismic reflection data

Cited by 26 publications

References 17 publications

Moment tensor solutions for small and moderate earthquakes in the Ibero‐Maghreb region

Moment tensor solutions for small and moderate earthquakes in the Ibero‐Maghreb region

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

Internal structure and kinematics of Variscan thrust sheets in the valley of the Trubia River (Cantabrian Zone, NW Spain): regional tectonic implications

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