Home › Orogen › Young Researchers

Eloise BESSIERE

Thesis: Évolution géodynamique des Zones Internes des Cordillères Bétiques (Andalousie, Espagne) : Apports d’une étude pluridisciplinaire du Complexe Alpujárride

Supervisor:
L. Jolivet (Université de Paris Sorbonne)

Major Results

The geodynamics of the Alboran Sea (Gibraltar Arc) and its peripheral fold-and-thrust belt units (Rif and Betic cordillera) is revisited by integrating field observations, Raman Spectroscopy, Ar/Ar dating and kinematic reconstructions. The kinematics of the Ronda peridotite (the largest body of subcontinental mantle at the Earth’s surface) is revised and interpreted as resulting from tectonic exhumation along a large-scale detachment fault during hyper-extension during a rifting episode, on still undetermined age (Miocene or Mesozoic). In addition, the main tectono-metamorphic events during the Alpine phase have been better constrained, (i) the HP/LT episode before 38 Ma and (ii) the HP/HT episode until 20 Ma.

Abstract

The Betic-Rif Cordillera, located in the western Mediterranean region, forms a narrow, arcuate orogenic belt. By comparison with other orogenic belts in the Mediterranean realm, its geodynamic evolution is highly controversial because of a long and complex tectono-metamorphic history, including the Mesozoic rifting and the Alpine orogenesis where subduction, collisional and post-orogenic extensional events are successively recorded. The Alpujárride Complex is the most important complex cropping out in the Internal Zones of the Betic Cordillera and mostly constitutes the basement of the Alboran Domain. The subdivision of this complex into type-units is based on stratigraphic, metamorphic and structural position criteria.

Each unit shows a consistent stratigraphic succession with local variations in relative thickness and paleogeographic environment. They appear bounded either by thrusts or extensional shear zones and normal faults affect this complex. One puzzling characteristic of the Alpujárride Complex is the metamorphic contrast between the western and central-eastern parts of this complex. Indeed, the central and eastern Alpujárride Complex units show many HP-LT relicts that are lacking in the western part, except for the retrogressed Ojén eclogites. These units are interpreted to have sunk during the subduction of a continental sliver, which then exhumed mantle on its roof during the slab rebound.

Paléogéographie et coupes à ~145 Ma avec la localisation des différents domaines d’intérêt, i.e. le Complexe Alpujárride de l’ouest, le Complexe Sebtide, le Complexe Nevado-Filabride et enfin le Complexe Alpujárride du centre et de l’est.

Coupe synthétique et schématique de la zone d’étude à ~9 Ma.

Géodynamique de la Méditerranée occidentale : une série de bassins d’arrière-arc dans un environnement montagneux.

Jolivet, L., Romagny, A., Augier, R., Bessière, E., Do Couto, D., Gorini, C., Caroir, F., & Suc, J.-P. (2019). Géodynamique de la Méditerranée occidentale : une série de bassins d’arrière-arc dans un environnement montagneux. Géochronique, 149, 20-26.

keywords: Western Mediterranean, Plate reconstructions, Slab retreat, Transfer zones, Exhumation, Weak crust.

télécharger l’article

Detailed tectonic reconstructions of the Western Mediterranean region for the last 35 Ma, insights on driving mechanisms.

Romagny, A., Jolivet, L., Menant, A., Bessière, E., Maillard, A., Canva, A., Thinon, I., 2020. Detailed tectonic reconstructions of the Western Mediterranean region for the last 35 Ma, insights on driving mechanisms. BSGF-Earth Sciences Bulletin 191, 37,.

keywords: Western Mediterranean, plate reconstructions, slab retreat, transfer zones, exhumation, weak crust

DOI: https://doi.org/10.1051/bsgf/2020040

PhD Thesis: Évolution géodynamique des Zones Internes des Cordillères Bétiques (Andalousie, Espagne) : Apports d’une étude pluridisciplinaire du Complexe Alpujárride.

Eloïse Bessière. Évolution géodynamique des Zones Internes des Cordillères Bétiques (Andalousie, Espagne) : Apports d’une étude pluridisciplinaire du Complexe Alpujárride. Sciences de la Terre. Université d’Orléans, 2019. Français. ⟨tel-02392008⟩

keywords: Rift inheritances, métamorphisme HP/BT, exhumation , hyper-extension, datations 40Ar/39Ar, RSCM, Dorsale Calcaire, Péridotite Ronda, Cordillères Bétiques, Complexe Alpujárride