Lithospheric structure of<scp>I</scp>beria and<scp>M</scp>orocco using finite‐frequency<scp>R</scp>ayleigh wave tomography from earthquakes and seismic ambient noise

Palomeras, Imma; Villaseñor, Antonio; Thurner, S.; Levander, A.; Muset, Josep Gallart; Harnafi, M.

doi:10.1002/2016gc006657

Cited by 77 publications

(142 citation statements)

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“…The Moho depth data compiled by Diaz et al () show large discrepancies, with values of 25–27 km in the southern border of the Guadalquivir Basin and 30–40 km beneath the External Betics. Our crustal model suggests a gentle crustal thickening from the Iberian Massif (30–32 km) to the External Betics and the Gibraltar Strait (~40 km) in very good agreement with Palomeras et al () (Figure ).…”

Section: Discussionsupporting

confidence: 90%

Deep Seated Density Anomalies Across the Iberia‐Africa Plate Boundary and Its Topographic Response

et al. 2019

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The modes in which the lithosphere deforms during continental collision and the mechanisms involved are not well understood. While continental subduction and mantle delamination are often invoked in tectonophysical studies, these processes are difficult to be confirmed in more complex tectonic regions such as the Gibraltar Arc. We study the present‐day density and compositional structure of the lithosphere along a transect running from South Iberia to North Africa crossing the western Gibraltar Arc. This region is located in the westernmost continental segment of the African‐Eurasian plates, characterized by a diffuse transpressive plate boundary. An integrated and self‐consistent geophysical‐petrological methodology is used to model the lithosphere structure variations and the thermophysical properties of the upper mantle. The crustal structure is mainly constrained by seismic experiments and geological data, whereas the composition of the lithospheric mantle is constrained by xenolith data. The results show large lateral variations in the topography of the lithosphere‐asthenosphere boundary. We distinguish different chemical lithospheric mantle domains that reproduce the main trends of the geophysical observables and the modeled P and S wave seismic velocities. A sublithospheric body colder than the surrounding mantle is needed beneath the Betics‐Rif to adjust the measured potential fields. We link this body to the Iberian slab localized just to the east of the profile and having some effect on the geoid and Bouguer anomalies. Local isostasy allows explaining most of the topography, but an elastic thickness higher than 10 km is needed to explain local misfits between the Atlas and the Rif Mountains.

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Section: Discussionsupporting

confidence: 90%

Deep Seated Density Anomalies Across the Iberia‐Africa Plate Boundary and Its Topographic Response

et al. 2019

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“…This domain, which still features middle and upper crust, is bounded by extensional detachments and will localize the wedging and subduction of the continental crust south of the Mesozoic plate boundary (under the Cantabrian Mountains). Although there are no deep seismic reflection images for the Basque-Cantabrian basin, the persistent thick crust found by other methods Palomeras et al, 2017;Ruiz et al, 2017) suggests continuity between the subducted crust of the Cantabrian Mountains and that of the central Pyrenees, although related with different Mesozoic plate configurations.…”

Section: Accepted Manuscriptmentioning

confidence: 78%

“…As an alternative, it may be argued that the PYROPE receiver function profiles do not image the true depth reached by the subducted lower crust, which may have arrived at greater depths beyond detection. However, other geophysical methods have failed in finding the Pyrenean crustal roots at greater depths (Torné et al, 2015;Díaz et al, 2016;Palomeras et al, 2017). For that interpretation, we propose that the removal of lower…”

Section: Vertical Distribution Of Shorteningmentioning

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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“…PRISM3D is a three‐dimensional P and S wave model for Iberia and north Africa based on several previously published geophysical models (Arroucau et al, ). In particular, the lithospheric structure of western Iberia in PRISM3D is a weighted average of the tomographic models of Monna et al (), Bezada et al (), Chevrot, Villaseñor et al (), Silveira et al (), Palomeras et al (), and Veludo et al (). The Moho geometry is inferred from receiver functions (Chevrot, Sylvander et al, ; Chevrot, Villaseñor et al, ; Dündar et al, ; Mancilla & Diaz, ; Salah et al, ) and seismic active source studies (Afilhado et al, ; Díaz & Gallart, ; Martínez‐Loriente et al, ; Sallarès et al, ).…”

Section: Active Seismicity Of the Western Ossa Morena Zonementioning

confidence: 99%

An Active Seismic Zone in Intraplate West Iberia Inferred From High‐Resolution Geophysical Data

et al. 2018

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Intraplate Iberia is a region of slow lithopsheric deformation (<1 mm/yr) with significant historical earthquake activity. Recent high‐quality instrumental data have shown that small‐magnitude earthquakes collapse along clusters and lineaments, which however do not bear a clear relationship to geologically mapped active structures. In this article, we investigate the controls of these earthquake clusters. In particular, we study two of the identified clusters—the Arraiolos and the Évora seismic zones (ASZ and ESZ), located in the Western Ossa Morena Zone, southwest Iberia. The ASZ marks a sharp boundary between a seismically active region to its south and a more quiet region to its north. We revise historical earthquakes in order to clarify whether earthquake activity in the region is persistent. We use data from a local network to compute accurate epicenters, focal depth, focal mechanisms, and spatiotemporal clustering, thus characterizing ongoing small‐scale fracturing. Finally, we analyze complementary data sets, including tomographic models, Global Navigation Satellite Systems data, magnetic anomalies, and gravity anomalies, in order to discuss the factors that control seismogenesis in the two seismic zones. Consistency between earthquake locations, focal mechanisms and Global Navigation Satellite Systems data suggests that the ASZ is an active right‐lateral shear zone, which divides two blocks within the Western Ossa Morena Zone. The ESZ seems to localize microseismicity due to its granitic lithology. These results suggest that high‐resolution geophysical data have the potential to reveal blocks with different seismogenic and rheological behaviors, which may be used to improve our understanding of fault systems and the assessment of earthquake hazard in slowly deforming regions.

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Lithospheric structure ofIberia andMorocco using finite‐frequencyRayleigh wave tomography from earthquakes and seismic ambient noise

Abstract: Key Points:• 3D shear wave velocity model of Iberia and north Morocco

Cited by 77 publications

References 84 publications

Deep Seated Density Anomalies Across the Iberia‐Africa Plate Boundary and Its Topographic Response

Deep Seated Density Anomalies Across the Iberia‐Africa Plate Boundary and Its Topographic Response

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

An Active Seismic Zone in Intraplate West Iberia Inferred From High‐Resolution Geophysical Data

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