For subduction dynamics, I dedicated my research work on the Betic-Rif Cordillera, located in the westernmost part of the Mediterranean region (Figure 1a). This orogenic belt is emblematic of Cenozoic chains of this region and shows a strongly arcuate shape. Arising from geological and geophysical observations, several geodynamic models, sometimes radically different, have been proposed and debated. One major obstacle explains these debates and notably the non-consensus about the timing of the alpine tectono-metamorphism events. A thermal event ending around 23-20 Ma reset many geochronometers (U/Pb, ⁴⁰Ar/³⁹Ar, Lu/Hf, Sm/Nd, fission tracks; Figure 1b). To tackle this issue, I followed during my PhD a trans- and multi-disciplinary approach, which allowed us to propose new kinematic reconstructions of the Betic-Rif Cordillera since the Mesozoic reconciling most of geological evidences (Figure 1c; Bessière et al., 2021a). Based on (i) geological and structural field surveys associated with (ii) petrological studies, (iii) Raman Spectroscopy on Carbonaceous Material (RSCM) and (iv) ⁴⁰Ar/³⁹Ar dating on micas by step heating - applied on the metamorphic Internal Zones and more precisely on the Alpujárride Complex - we thus showed that (i) the outcropping sub-continental peridotite massifs were exhumed in a hyper-extension setting (Bessière et al., 2021b), maybe during the Mesozoic rifting, while (ii) the HP/LT alpine metamorphic event occurred during the Eocene (Bessière et al., 2022) and not during the Miocene as it was claimed so long.

This research was significant because providing a new tectono-metamorphic timing with an original peridotite emplacement model (previously considered as the mantle wedge extrusion during Oligo-Miocene transpressional tectonics) as well as the first Eocene dating for the alpine HP/LT metamorphism event.

Figure 1: (A) Location map of the Betic-Rif Cordillera in the Mediterranean region.

(B) Synthesis of the main timing constraints on the tectono-metamorphic events (before our results). Modified after Bessière, 2019.

(C) Example of kinematic reconstructions (after our results). Modified after Bessière et al., 2021.

More recently, I started to work on the heat flow and its prediction either at global or local scale, mainly on behalf of TotalEnergies. A better knowledge of the thermicity and its evolution through space and time is a crucial point to improve our understanding of sedimentary basins and orogen dynamics. Indeed, temperature is a critical parameter involved in many aspects of the orogen life, controlling the formation and destabilization of minerals, as well as the localization of deformation or fluid circulations. The relationships between fluid circulations, tectonic structures and the localization of heat flow anomalies remain unclear.

In addition of field skills, e.g., structural and metamorphic cartography, petrological observations..., as well as the use of chemical composition scanners, e.g., SEM and EMPA, two major technical facilities have been used during my research activities: the Raman Spectroscopy on Carbonaceous Material (RSCM) and the ⁴⁰Ar/³⁹Ar dating by step heating.