Based on gravity analysis and previous integrated studies combining potential fields and seismic ... more Based on gravity analysis and previous integrated studies combining potential fields and seismic data, we demonstrate that the Iberia-Africa plate boundary region is characterized by several tectonically inverted transtensional domains inherited from the Jurassic. Gravity data, when filtered for short wavelengths, show conspicuous positive Bouguer anomalies associated with the Gorringe Bank, the Guadalquivir Bank and the Ronda/Beni-Bousera peridotitic massifs. Gravity modelling combined with seismic and geological data shows that the filtered Bouguer anomalies are compatible with relatively high-density and shallow-buried bodies, which correspond to partly serpentinized peridotitic slices with similar densities and geometries as those proved for the Gorringe Bank. The study indicates that the Alpine convergence between Africa and Iberia since Late Cretaceous times reactivated these transtensional domains, which were less deformed westwards and thus preserved their segmentation. The interpretation of these Bouguer anomalies and their distribution substantiates the double-polarity subduction model proposed for the region, and agrees with the present-day seismically diffuse character of the Iberia-Africa plate boundary.Peer Reviewe
The ESCIN-3.1 profile was acquired in 1993 offshore northwest Galicia (Spain), and recorded 20 s ... more The ESCIN-3.1 profile was acquired in 1993 offshore northwest Galicia (Spain), and recorded 20 s of near vertical reflection seismic data. This 140 km long profile was intended to provide an image of the crustal structure of this sector of the continental margin from near the coastline to the deep-sea area. The tectonic evolution of the northwest Galicia margin initiated by rifting during Late Jurassic-Early Cretaceous times and progressed to sea floor spreading during Albian- Late Cretaceous times when the Bay of Biscay opened. Subsequently, the margin was active during the convergence of Eurasia and Iberia in the Late Oligocene to Early Miocene. Here we present a new interpretation of the mentioned profile based on a newly reprocessed depth migrated image and corresponding gravity model. In the deep-sea areas, a free-air gravity low reach up to - 120 mGal and the sea bottom is at more than 5000 m deep. The 7 km thick flat lying undisturbed sedimentary cover appears above a 10 km thick, ~120 Ma old oceanic basement. This flat sediments onlap toward the ocean-continent transition on a folded and disturbed 20 km long wedge shaped sedimentary body. A major landward dipping structure reaches from the foot of the slope to beneath the sub horizontal Moho of the continental slope. The slope has a gentle dip of about 2° in this section, and include large mass flow deposits. Fault bound sediments are imaged in the upper continental margin that could correspond to preserved syn-rift Mesozoic structures. The structure of what correspond to the continental basement in the thicker part of the margin is not well resolved. Only in the landward side of the profile a layered lower crust is seen where the Moho reaches depths of 29 km. The ocean-continent transition in this profile may be interpreted as that of an active compressional boundary with some accretion of deep-sea sediments that are underthrust by a thinned continental margin with large submarine landslides and mass flow deposits evidence of the massive failure along the continental slope.Peer Reviewe
Documento elaborado por la Comision para la Coordinacion y Racionalizacion de Infraestructuras Ci... more Documento elaborado por la Comision para la Coordinacion y Racionalizacion de Infraestructuras Cientificas y Tecnicas Singulares (ICTS) y participacion en Infraestructuras Europeas de Investigacion (IEI), compuesta por los siguientes miembros: Montserrat Torne i Escasany (Presidencia); Jose Luis de Miguel Anton y Jose Vicente Garcia Ramos (Vicepresidencia); Vocales: Carmen Garcia Garcia (Fisica e Ingenieria); Jose Maria Carazo Garcia (Biologia, Salud y Alimentos); Joaquin Tintore Subirana (Medio ambiente y Ciencias de la Tierra); Isabel Campos Plasencia (Tec. de la Informacion y la comunicacion); Julio Perez Diaz (Humanidades y CCSS); Monica Martin Lanuza (Organizacion Central del CSIC y Secretaria).
Deep seismic profiling and gravity data show that the continental crust under the Valencia trough... more Deep seismic profiling and gravity data show that the continental crust under the Valencia trough has been thinned by up to a factor of three in the centre, and that the uppermost mantle there has an unusually low density. Structural mapping in the borders of the Valencia trough shows important asymmetry, and there are asymmetrical features in the geophysical modelling. There are many aspects of the basin formation that are still to be worked out
Topo-Europe Conference, 5–10 May 2019, Granada, SpainThe present-day density and compositional 2D... more Topo-Europe Conference, 5–10 May 2019, Granada, SpainThe present-day density and compositional 2D structure of the lithosphere is studied along a ~950-km-long transect crossing the Gibraltar Arc System and Atlas Mountains. The transect runs from the tectonically stable Variscan Iberian Massif (North) to the deformed alpine tectonic domains of the Gibraltar Arc System and the Atlas intracontinental orogenic belt (South). Both domains are located in the westernmost continental segment of the African-Eurasian plates, a segment which is characterized by a diffuse transpressive plate boundary. An integrated and self-consistent geophysical-petrological methodology is used to model the along transect variations of the crust structure and the thermophysical properties of the lithosphere and sublithospheric mantle. The crust is mainly constrained by active and passive-source seismic experiments and available geological data, whereas the composition of the lithospheric mantle is constrained by xenolith data and tomography models. Results highlight large lateral variations in the topography of the lithosphere-asthenosphere boundary (LAB). We distinguish different chemical lithospheric mantle domains that reproduce the main trends of the geophysical observables and the recorded P- and S-wave seismic velocities. To reproduce the low velocity regions imaged by tomography below the Iberian Massif and the Atlas Mountains and at the same time constrain the surface geophysical data, we had to define two sublithospheric mantle anomalies (+80ºC) beneath those regions. A cold body (-220ºC) of lithospheric material composition beneath the External Betics-Rif is needed to adjust the measured geoid height and bouguer anomaly. This body is interpreted as the Iberian slab observed on a W-E tomographic profile, localized just to the east of the profile and having some effect on the geoid and Bouguer anomalies. Elastic thickness of 10 km is enough to adjust the topography in most of the profile, but higher values are necessary between the Atlas and the Rif Mountains
Based on gravity analysis and previous integrated studies combining potential fields and seismic ... more Based on gravity analysis and previous integrated studies combining potential fields and seismic data, we demonstrate that the Iberia-Africa plate boundary region is characterized by several tectonically inverted transtensional domains inherited from the Jurassic. Gravity data, when filtered for short wavelengths, show conspicuous positive Bouguer anomalies associated with the Gorringe Bank, the Guadalquivir Bank and the Ronda/Beni-Bousera peridotitic massifs. Gravity modelling combined with seismic and geological data shows that the filtered Bouguer anomalies are compatible with relatively high-density and shallow-buried bodies, which correspond to partly serpentinized peridotitic slices with similar densities and geometries as those proved for the Gorringe Bank. The study indicates that the Alpine convergence between Africa and Iberia since Late Cretaceous times reactivated these transtensional domains, which were less deformed westwards and thus preserved their segmentation. The interpretation of these Bouguer anomalies and their distribution substantiates the double-polarity subduction model proposed for the region, and agrees with the present-day seismically diffuse character of the Iberia-Africa plate boundary.Peer Reviewe
The ESCIN-3.1 profile was acquired in 1993 offshore northwest Galicia (Spain), and recorded 20 s ... more The ESCIN-3.1 profile was acquired in 1993 offshore northwest Galicia (Spain), and recorded 20 s of near vertical reflection seismic data. This 140 km long profile was intended to provide an image of the crustal structure of this sector of the continental margin from near the coastline to the deep-sea area. The tectonic evolution of the northwest Galicia margin initiated by rifting during Late Jurassic-Early Cretaceous times and progressed to sea floor spreading during Albian- Late Cretaceous times when the Bay of Biscay opened. Subsequently, the margin was active during the convergence of Eurasia and Iberia in the Late Oligocene to Early Miocene. Here we present a new interpretation of the mentioned profile based on a newly reprocessed depth migrated image and corresponding gravity model. In the deep-sea areas, a free-air gravity low reach up to - 120 mGal and the sea bottom is at more than 5000 m deep. The 7 km thick flat lying undisturbed sedimentary cover appears above a 10 km thick, ~120 Ma old oceanic basement. This flat sediments onlap toward the ocean-continent transition on a folded and disturbed 20 km long wedge shaped sedimentary body. A major landward dipping structure reaches from the foot of the slope to beneath the sub horizontal Moho of the continental slope. The slope has a gentle dip of about 2° in this section, and include large mass flow deposits. Fault bound sediments are imaged in the upper continental margin that could correspond to preserved syn-rift Mesozoic structures. The structure of what correspond to the continental basement in the thicker part of the margin is not well resolved. Only in the landward side of the profile a layered lower crust is seen where the Moho reaches depths of 29 km. The ocean-continent transition in this profile may be interpreted as that of an active compressional boundary with some accretion of deep-sea sediments that are underthrust by a thinned continental margin with large submarine landslides and mass flow deposits evidence of the massive failure along the continental slope.Peer Reviewe
Documento elaborado por la Comision para la Coordinacion y Racionalizacion de Infraestructuras Ci... more Documento elaborado por la Comision para la Coordinacion y Racionalizacion de Infraestructuras Cientificas y Tecnicas Singulares (ICTS) y participacion en Infraestructuras Europeas de Investigacion (IEI), compuesta por los siguientes miembros: Montserrat Torne i Escasany (Presidencia); Jose Luis de Miguel Anton y Jose Vicente Garcia Ramos (Vicepresidencia); Vocales: Carmen Garcia Garcia (Fisica e Ingenieria); Jose Maria Carazo Garcia (Biologia, Salud y Alimentos); Joaquin Tintore Subirana (Medio ambiente y Ciencias de la Tierra); Isabel Campos Plasencia (Tec. de la Informacion y la comunicacion); Julio Perez Diaz (Humanidades y CCSS); Monica Martin Lanuza (Organizacion Central del CSIC y Secretaria).
Deep seismic profiling and gravity data show that the continental crust under the Valencia trough... more Deep seismic profiling and gravity data show that the continental crust under the Valencia trough has been thinned by up to a factor of three in the centre, and that the uppermost mantle there has an unusually low density. Structural mapping in the borders of the Valencia trough shows important asymmetry, and there are asymmetrical features in the geophysical modelling. There are many aspects of the basin formation that are still to be worked out
Topo-Europe Conference, 5–10 May 2019, Granada, SpainThe present-day density and compositional 2D... more Topo-Europe Conference, 5–10 May 2019, Granada, SpainThe present-day density and compositional 2D structure of the lithosphere is studied along a ~950-km-long transect crossing the Gibraltar Arc System and Atlas Mountains. The transect runs from the tectonically stable Variscan Iberian Massif (North) to the deformed alpine tectonic domains of the Gibraltar Arc System and the Atlas intracontinental orogenic belt (South). Both domains are located in the westernmost continental segment of the African-Eurasian plates, a segment which is characterized by a diffuse transpressive plate boundary. An integrated and self-consistent geophysical-petrological methodology is used to model the along transect variations of the crust structure and the thermophysical properties of the lithosphere and sublithospheric mantle. The crust is mainly constrained by active and passive-source seismic experiments and available geological data, whereas the composition of the lithospheric mantle is constrained by xenolith data and tomography models. Results highlight large lateral variations in the topography of the lithosphere-asthenosphere boundary (LAB). We distinguish different chemical lithospheric mantle domains that reproduce the main trends of the geophysical observables and the recorded P- and S-wave seismic velocities. To reproduce the low velocity regions imaged by tomography below the Iberian Massif and the Atlas Mountains and at the same time constrain the surface geophysical data, we had to define two sublithospheric mantle anomalies (+80ºC) beneath those regions. A cold body (-220ºC) of lithospheric material composition beneath the External Betics-Rif is needed to adjust the measured geoid height and bouguer anomaly. This body is interpreted as the Iberian slab observed on a W-E tomographic profile, localized just to the east of the profile and having some effect on the geoid and Bouguer anomalies. Elastic thickness of 10 km is enough to adjust the topography in most of the profile, but higher values are necessary between the Atlas and the Rif Mountains
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