Mountain Front Development by Folding and Crustal Thickening in the Internal Zone of the Betic Cordillera-Alboran Sea Boundary |
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| Authors: | Carlos Marín-Lechado Jesús Galindo-Zaldívar Luís Roberto Rodríguez-Fernández Antonio Pedrera |
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| Institution: | 1.Instituto Geológico y Minero de Espa?a,Granada,Spain;2.Departamento de Geodinámica,Universidad de Granada,Granada,Spain |
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| Abstract: | The boundary between the Alboran Sea and Betic Cordillera is a good example of a fold related mountain front in the Internal
Zone of an alpine mountain range. Since the late Miocene, NNW-SSE convergence between the Eurasian and African plates has
produced shortening and related orthogonal extension. To improve the characterisation of the geometry of the deep structure
in the region and to establish the recent tectonic evolution of the mountain front, well logs and newly acquired geophysical
data (multichannel reflection seismic and gravimetric surveys) have been interpreted and integrated with available surface
data. The most marked tectonic structure corresponds to large antiforms and synforms of ENE-WSW trend which are related to
mountain ranges and basins, respectively. The fold belt continues toward the northern continental shelf of the Alboran Sea.
The fold vergence is generally northwards and its amplitude decreases progressively towards SSE, until disappearring in a
sharp boundary where the reflectors are undeformed. The deep geometry suggests that fold growth started during upper Tortonian
times and continued its activity up to Pliocene or even Quaternary times. The NNW-SSE compression produces crustal thickening
and a regional and progressive southwards emersion. The location of main present-day deformation fronts in the Internal Zones
contrasts with classical models where the deformation progresses towards the frontal part of External Zones of cordilleras.
In addition, this fold-related deformation mountain front has features different from fault related fronts, as it does not
show a sharp boundary, and folds that determine rectilinear mountain boundaries decrease progressively in amplitude or in
wavelength up to undeformed areas. |
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| Keywords: | Active folds Neogene-Quaternary basin continental uplift geophysical prospecting western Mediterranean |
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