Tectono-geomorphological evolution of the Eastern Pyrenees: Insights from thermo-kinematic modeling

Abstract

Constraining the tectono-geomorphological evolution of the Pyrenees is still a major challenge, especially in the Eastern Pyrenees where late Neogene exhumation history and topographic evolution appear contrasted and have been debated. In this study, we performed thermo-kinematic (Pecube) modeling using a relatively dense spatial compilation of previously-published low-temperature thermochronological data for the Eastern Pyrenees, and quantified the late-Neogene exhumation history based on different topographic evolution models reconstructed from literature constraints. Our modeling outcomes suggest a major decrease in the regional exhumation rate between 37 and 35 Ma, associated to an early-end contractional tectonics for the Eastern Pyrenees. Two main periods of the Têt fault normal activity have been characterized, with the existence of pluri-kilometric (2–3 km) post- Oligocene-Miocene displacement along the western segment of the Têt fault. The different topographic evolution models show relatively similar results for the regional exhumation since ca. 35 Ma and for the most recent (mid to late-Miocene) tectonic event recorded along the Têt fault. Conversely, inversion results obtained for pre-35 Ma regional exhumation rates, and more importantly for the Oligocene-Miocene activity of the Têt fault appear contrasted between the investigated topographic scenarios. Overall, this study confirmed a mid to late Miocene significant extensional tectonic event for the Eastern Pyrenees, which may have had a non-negligible role in late-stage relief evolution for this part of the orogen. However, deciphering the long-term evolution of topographic relief through thermo-kinematic modeling appears still challenging for slowly-exhuming mountain ranges given the limited resolution of low-temperature thermochronological data to topographic changes.