Tracing the evolution of depositional systems from the late Carboniferous to the Early Triassic in the Central Pyrenees (Erillcastell Basin): a tectono-stratigraphic approach
| Autor: | Lloret, Joan, Ronchi, Ausonio, López-Gómez, José, Arche, Alfredo, Horra, Raúl de la, Barrenechea, J. F., Gretter, Nicola |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | Trabajo presentado en el 33rd International Meeting of Sedimentology y 16ème Congrès Français de Sédimentologie (2017), celebrado en Toulouse (Francia), del 10 al 12 de octubre de 2017 The late Carboniferous-Lower Triassic basins of the Central-eastern Pyrenees are the result of the postorogenic transtension and extension after the Variscan orogeny. Several intramontane continental troughs formed in SW Europe following the Upper Carboniferous-Lower Permian crustalscale dextral shearing. In this geodynamic scenario, a strong tectonic control influenced the infills and geometries of the basins. In particular, their genesis is linked to the onset of post-collisional strike-slip tectonic regime followed, in the Cisuralian, by a more extensional setting with fluvial and lacustrine facies, accompanied by extensive pyroclastic deposition. Small and elongate fault-bounded basins expose a complete Late Palaeozoic continental volcano-sedimentary succession sealed by the widespread extensional Triassic sedimentation. The Upper Carboniferous–Lower Triassic stratigraphic record has been organized in four major sedimentary cycles grouping five litostratigraphic units. From oldest to youngest: the Grey Unit (GU – Upper Carboniferous), the Transition Unit (TU – earlyLowerPermian), the Lower Red Unit (LRU – late Lower Permian), the Upper Red Unit (URU – early Middle Permian) and the Buntsandstein facies (BUNT – Lower-Middle Triassic). The tectonostratigraphic evolution of four Upper Carboniferous – Lower Triassic basins was analyzed in Central-eastern Pyrenees. In order to better characterize each basin, this research is focused on multidisciplinary approach, linking sedimentology, tectonics, paleontology, and radiogenic isotope analysis. From W to E the four basins studied are the Castejón-Laspaúles, Erillcastell, Gramós, and Castellar-Camprodón. New stratigraphic data show some differences between the basins. Among others, the absence of the URU in the more westerly areas (i.e. ErillCastell and Castejón-Laspaúles) represents an important issue. Despite paleotopographic highs isolating the various sub-basins, other important fact is the single unit's thickness variation inside the troughs. From west to east, only the basal GU looks deposed with homogeneous hectometer thickness with only local variations. The three Permian units (TU, LRU and URU) are thinner towards the west up to areas where the URU is completely lacking. The important syn-tectonic fault control in the western strike-slip basins together with the performed structural analysis indicate that the URU never deposited in those basins. From our detailed sedimentological study in the Erillcastell, Gramós and Castellar-Camprodón basins, we can state that: 1) the Upper Carboniferous-earliest Permian deposits show very similar features in all of them; 2) during the Early Permian, coarse-grained sediments and more channelized deposits developed in the eastern-central basins, i.e Castellar-Camprodón and Gramós and became finer and related to sand flats or playa-lake settings to the west; 3) the Buntsandstein shows again homogeneous facies and thicknesses everywhere. As a whole, the geological evolution in this wide context can be assumed as a proxy to understand the tectono-stratigraphic basin history as a consequence of a post-collisional regime in the collapse phases of an orogenic chain. In particular the Erillcastell Basin is a very good reference to show how tectonics controls the sedimentary deposition during the final stages of the Variscan orogenesis |
| Databáze: | OpenAIRE |
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