Deciphering the Cenozoic Exhumation History of the Eastern Pyrenees Along a Crustal‐Scale Normal Fault Using Low‐Temperature Thermochronology

Abstract

In orogenic belts, crustal-scale faults are key deformation markers that accommodate various regimes of plate tectonics during rock burial, exhumation or strike slip activity (

Fault Gouge Dating in the Spanish Pyrenees: Fault Ages, Thrust Propagation Sequence, Wall‐Rock Provenance, and Thermal Constraints

“…The coeval ages of thrusting on many faults in multiple regions of the Pyrenees during the Middle and Late Eocene demonstrate that the range effectively behaved as a doubly tapered critical wedge, analogous to the no-backstop critical wedge model (sensu Dahlen et al, 1984). Contemporaneously, normal faulting in the eastern end of the Axial Zone began at 35 Ma, further suggesting a latest Eocene shift in the dynamics of the range (Milesi et al, 2022). The eastern end of the range records localized extension within the Axial Zone, related to the opening of the Gulf of Lyon, evidenced by modeling of 43-18 Ma apatite (U-Th)/He cooling ages sampled across the Têt normal nault (Milesi et al, 2022).…”

“…Contemporaneously, normal faulting in the eastern end of the Axial Zone began at 35 Ma, further suggesting a latest Eocene shift in the dynamics of the range (Milesi et al, 2022). The eastern end of the range records localized extension within the Axial Zone, related to the opening of the Gulf of Lyon, evidenced by modeling of 43-18 Ma apatite (U-Th)/He cooling ages sampled across the Têt normal nault (Milesi et al, 2022). No similar late Eocene extension has been documented in the central or western portions of the range.…”

Seismic Activity at the Eastern Pyrenean Termination

“…Focal mechanisms projected in depth along the WSW-ENE cross-section show a nodal plane deepening to the ENE, parallel to the earthquake distribution in depth. These events could be related to the NW-SE oriented Fontpédrouse Fault (Milesi et al, 2022). Further east, a few isolated events have also been recorded in the northern edge of the Conflent Basin.…”

“…Briais et al, 1990). To the south-east, the Tech Fault runs subparallel to the Têt Fault for approximately 40 km in the ENE-WSW direction between the Canigó Massif and the Mediterranean coast, displacing the Variscan structures of the Alberas Massif and limiting the Roussillon Basin to the south (Briais et al, 1990;Milesi et al, 2022).…”

“…The basin is bounded on the east by the Têt Fault, a major accident formed by NE-SW and E-W oriented north-dipping normal faults extending along approximately 120 km, separating the Canigó, Carançà and Puigmal massifs from the Neogene infill to the NW. The Têt Fault has been active since the Eocene, as indicated by fission track ages (Milesi et al, 2022), extends down at least through the upper crust and has generated high-relief massifs in its footwall (Briais et al, 1990;Milesi et al, 2022;Calvet et al, 2021). However, the current activity of the Têt Fault is under debate as there are no clear evidences of current seismic activity (IGME, 2022).…”