Denudation history and palaeogeography of the Pyrenees and their peripheral basins: an 84-million-year geomorphological perspective

This review provides a synthesis of the evolution of the Pyrenees since -84 Ma and is uniquely focused on analysing jointly and comparatively its peripheral proforeland, retro-foreland and Mediterranean basins. The reconstructions adopt a geomorphological perspective focused on the waxing and waning of palaeorelief, and is underpinned by (i) the denudation history of the mountain belt encoded in the sedimentary record of its basins, (ii) rock-cooling histories inferred from lowtemperature thermochronology, and (iii) the age and spatial distribution of tectonic and erosional landforms. Existing geological reconstructions of the Pyrenees commonly terminate at the end of the syntectonic collision period (early Miocene). Here, the no-less eventful post-shortening period of the last 25?30 m.y. is also addressed. Accordingly, emphasis is given to the record provided by nonmarine clastic sequences, and to the often understated depositional biochronology documented by the continental fossils they contain. Sedimentological and provenance analysis of coarse clastic deposits further documents the fine-scale palaeogeography of sources and sinks, and is correlated with different generations of eustatic, tectonic, and volcanic features, as well as extant populations of land surfaces such as rock pediments, palaeovalleys, and other landforms indicative of palaeoelevation and palaeotopography. These interconnected and age-bracketed diagnostic features are correlated with independent evidence concerning the structural evolution of the orogenic belt at crustal and lithospheric scale. They show that the Ancestral (i.e., Paleogene) Pyrenees were in many aspects dissimilar to the successor mountain range we observe today. They also suggest that, despite its prima facie topographic continuity from the Mediterranean to the Atlantic, the modern mountain range, particularly in its eastern half, is in a transient topographic state. This would appear to have been driven by large-scale asthenospheric flows contributing to regional uplift and erosion of not just the mountain range but also its foreland basins during This review provides a synthesis of the evolution of the Pyrenees since-84 Ma and is uniquely focused on analysing jointly and comparatively its peripheral pro foreland, retro-foreland and Mediterranean basins. The reconstructions adopt a geomorphological perspective focused on the waxing and waning of palaeorelief, and is underpinned by (i) the denudation history of the mountain belt encoded in the sedimentary record of its basins, (ii) rock-cooling histories inferred from low temperature thermochronology, and (iii) the age and spatial distribution of tectonic and erosional landforms. Existing geological reconstructions of the Pyrenees commonly terminate at the end of the syntectonic collision period (early Miocene). Here, the no-less eventful post-shortening period of the last 25?30 m.y. is also addressed. Accordingly, emphasis is given to the record provided by nonmarine clastic sequences, and to the often understated depositional biochronology documented by the continental fossils they contain. Sedimentological and provenance analysis of coarse clastic deposits further documents the fine-scale palaeogeography of sources and sinks, and is correlated with different generations of eustatic, tectonic, and volcanic features, as well as extant populations of land surfaces such as rock pediments, palaeovalleys, and other landforms indicative of palaeoelevation and palaeotopography. These interconnected and age-bracketed diagnostic features are correlated with independent evidence concerning the structural evolution of the orogenic belt at crustal and lithospheric scale. They show that the Ancestral (i.e., Paleogene) Pyrenees were in many aspects dissimilar to the successor mountain range we observe today. They also suggest that, despite its prima facie topographic continuity from the Mediterranean to the Atlantic, the modern mountain range, particularly in its eastern half, is in a transient topographic state. This would appear to have been driven by large-scale asthenospheric flows contributing to regional uplift and erosion of not just the mountain range but also its foreland basins during the last-12 m.y.

Automated summary

This review provides a synthesis of the evolution of the Pyrenees since -84 Ma, focusing on its peripheral proforeland, retro-foreland, and Mediterranean basins. It adopts a geomorphological perspective and analyzes the waxing and waning of palaeorelief through denudation history, rock-cooling histories, and tectonic and erosional landforms. The study highlights the dissimilarities between the Ancestral Pyrenees and the modern mountain range, suggesting a transient topographic state driven by large-scale asthenospheric flows.