Mesozoic extension and Cenozoic contraction in the Eastern Iberian Chain (Maestrat Basin) = Tectònica extensiva mesozoica i contractiva cenozoica a la Cadena Ibèrica oriental
The Maestrat basin was one of the most subsident basins of the Iberian Rift System, which experienced two main rifting events: Late Permian-Late Triassic and Late Jurassic-Early Cretaceous. Its inversion during the Cenozoic Alpine orogeny generated the E-W-trending, N-verging Portalrubio–Vandellòs f...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/403983 |
| Acceso en línea: | http://hdl.handle.net/10803/403983 |
| Access Level: | acceso abierto |
| Palabra clave: | Geologia estructural Geología estructural Structural geology Maestrat (País Valencià i Aragó : Regió) Maestrazgo (Comunidad Valeanciana y Aragón : Región) Maestrazgo (Valencian Community and Aragon : Region) Tectònica Tectónica Tectonics Ciències Experimentals i Matemàtiques 55 |
| Sumario: | The Maestrat basin was one of the most subsident basins of the Iberian Rift System, which experienced two main rifting events: Late Permian-Late Triassic and Late Jurassic-Early Cretaceous. Its inversion during the Cenozoic Alpine orogeny generated the E-W-trending, N-verging Portalrubio–Vandellòs fold-and-thrust belt in the Linking Zone between the NW-SE-trending Iberian Chain, and the NE-SW-trending Catalan Coastal Chain, detached in the Triassic evaporites, while southwards it also involved the Variscan Basement. The study area is located in the central part of the fold-and-thrust belt. The objectives of this thesis are to characterize the structures developed during the different deformation events, as well as to characterize the transition from thin to thick-skinned areas. Finally, it aims to propose a kinematic evolutionary model for the northern margin of the basin based on the interpretation of subsurface data and new field data. During the first stage of extensional activity a high angle normal fault system developed, which fragmented the Variscan Basement into a system of horsts, grabens and half-grabens. Those faults were active during the deposition of the Buntsandstein facies and lasted until the lower part of the Middle Muschelkalk facies was deposited, filling the system of horsts and grabens and generating depositional thickness variations. The fault system was overstepped by the upper part of the Middle Muschelkalk, indicating a decrease in the extensional activity that lasted until the carbonates of the Upper Muschelkalk facies were deposited, as they present nearly constant thickness. During the Keuper facies deposition, the extensional activity of some normal faults in the acoustic basement resumed, triggering the Middle Muschelkalk salt flow, which developed salt anticlines and welds, increasing the thickness variations of this facies. The age of the salt flow is deduced from the Keuper facies reflectors lapping on the folded Upper Muschelkalk above the salt accumulations. Growth-strata above some Upper Muschelkalk forced folds are also recognized, developed above some reactivated normal faults in the basement. During the second stage of extensional activity, a system of segmented listric normal faults, connected by relay ramps developed bounding the different sub-basins. The Maestrat basin filling (Upper Jurassic-Lower Cretaceous) broadly becomes thinner towards the north, towards the northern boundary of the basin, although locally it becomes thicker northwards, towards the hanging wall of the S-dipping main normal faults. Major extension occurred during the Barremian, as units of this age display bigger thickness variations, while the Aptian units show more constant thicknesses. During the Cenozoic Alpine orogeny, the Maestrat basin was inverted. The E-W-trending, N-verging Maestrat Basement Thrust developed, traversing the entire basin, as a result of the inversion of the Mesozoic fault system within the basement. As this thrust reached the Mesozoic cover, it propagated across the Middle Muschelkalk detachment level, transporting the supra-salt cover, and the normal fault segments within it, about 12km towards the North. The basement thrust is deduced to have a ramp-flat geometry, with a low-dip ramp which reaches about 8km depth, rooted in the upper crust. The displacement of the basement in the hanging wall of this ramp generated a 40km-wide uplifted area, in the N-S direction, bounded to the N by the Calders monocline, interpreted as a fault-bend-fold adapted to the ramp to flat transition in the basement thrust. It also indicates the transition from a thick-skinned style of deformation in the S, to a thin-skinned style to the N. The superficial shortening accumulated in the northern margin of the basin, containing the thinnest Mesozoic cover, developing the Portalrubio-Vandellòs fold-and-thrust belt. |
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