What can seismic noise tell us about the Alpine reactivation of the Iberian Massif? An example in the Iberian Central System
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Published:2020-12-18
Issue:6
Volume:11
Page:2499-2513
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ISSN:1869-9529
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Container-title:Solid Earth
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language:en
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Short-container-title:Solid Earth
Author:
Andrés JuvenalORCID, Ayarza PuyORCID, Schimmel MartinORCID, Palomeras ImmaORCID, Ruiz MarioORCID, Carbonell RamonORCID
Abstract
Abstract. The Iberian Central System, formed after the Alpine
reactivation of the Variscan Iberian Massif, features maximum altitudes of
2500 m. It is surrounded by two foreland basins with contrasting elevation: the Duero Basin to the north, located at 750–800 m, and the Tajo Basin to the south,
lying at 450–500 m. The deep crustal structure of this mountain range seems
to be characterized by the existence of a moderate crustal root that
provides isostatic support for its topography. New seismic data are able to
constrain the geometry of this crustal root, which appears to be defined by
a northward lower-crustal imbrication of the southern Central Iberian crust
underneath this range. Contrarily to what was expected, this imbrication
also affects the upper crust, as the existing orogen-scale mid-crustal
Variscan detachment was probably assimilated during the Carboniferous
crustal melting that gave rise to the Central System batholith. In addition,
the lower crust might have thinned, allowing coupled deformation at both
crustal levels. This implies that the reactivated upper-crustal fractures
can reach lower-crustal depths, thus allowing the entire crust to sink. This
new model can explain the differences in topography between the Central
System foreland basins. Also, it provides further constraints on the crustal
geometry of this mountain range, as it seems to be that of an asymmetric
Alpine-type orogen, thus hindering the existence of buckling processes as
the sole origin of the deformation. The results presented here have been
achieved after autocorrelation of seismic noise along the CIMDEF (Central Iberian Massif DEFormation Mechanisms) profile.
Although the resolution of the dataset features limited resolution (0.5–4 Hz, stations placed at ∼ 5 km), this methodology has allowed
us to pinpoint some key structures that helped to constraint the deformation
mechanisms that affected Central Iberia during the Alpine orogeny.
Funder
Ministerio de Ciencia e Innovación Consejería de Educación, Junta de Castilla y León Generalitat de Catalunya
Publisher
Copernicus GmbH
Subject
Paleontology,Stratigraphy,Earth-Surface Processes,Geochemistry and Petrology,Geology,Geophysics,Soil Science
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