Spatio-temporal patterns of Pyrenean exhumation revealed by inverse thermo-kinematic modeling of a large thermochronologic data set

Abstract

Large thermochronologic data sets enable orogen-scale investigations into spatio-temporal patterns of erosion and deformation. We present the results of a thermo-kinematic modeling study that examines large-scale controls on spatio-temporal variations in exhumation as recorded by multiple low-temperature thermochronometers in the Pyrenees mountains (France/Spain). Using 264 compiled cooling ages spanning ~200 km of the orogen, a recent model for its topographic evolution, and the thermo-kinematic modeling code Pecube, we evaluated two models for Axial Zone (AZ) exhumation: (1) thrust sheet–controlled (north-south) exhumation, and (2) along-strike (east-west) variable exhumation. We also measured the degree to which spatially variable post-orogenic erosion influenced the cooling ages. We found the best fit for a model of along-strike variable exhumation. In the eastern AZ, rock uplift rates peak at ≥1 mm/yr between 40 and 30 Ma, whereas in the western AZ, they peak between 30 and 20 Ma. The amount of post-orogenic (<20 Ma) erosion increases from <1.0 km in the eastern Pyrenees to >2.5 km in the west. The data reveal a pattern of exhumation that is primarily controlled by structural inheritance, with ancillary patterns reflecting growth and erosion of the antiformal stack and post-orogenic surface processes.

Deciphering the Cenozoic exhumation history of the Eastern Pyrenees along a crustal-scale normal fault using low-temperature thermochronology

“…After 35 Ma, low cooling rates are consistent with an important decrease in exhumation toward present-day in the Têt-fault hanging wall (Figure 5a). This is in agreement with the recent exhumation model for the Axial Zone proposed by Curry et al (2021). On the basis of a regional thermochronological data compilation and thermo-kinematic modeling (for details see Curry et al, 2021), this exhumation model suggests that rock uplift rates peak at 30-40 Ma in the Eastern Pyrenees, about 10 Ma earlier than in the western Pyrenees (see also Fillon & van der Beek, 2012 for a similar conclusion).…”

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

“…(2021). On the basis of a regional thermochronological data compilation and thermo‐kinematic modeling (for details see Curry et al., 2021), this exhumation model suggests that rock uplift rates peak at 30–40 Ma in the Eastern Pyrenees, about 10 Ma earlier than in the western Pyrenees (see also Fillon & van der Beek, 2012 for a similar conclusion).…”

Variable thermal histories across the Pyrenees orogen recorded in modern river sand detrital geo‐/thermochronology and PECUBE thermokinematic modelling

“…The tectonic framework of the forward model presented here is based on research that established fault geometries, location, vergence, slip, and exhumation rates and timing (Bernard et al, 2019; Curry et al, 2021; Muñoz, 1992; Sinclair et al, 2005; Waldner et al, 2021) that uses a tectonic model based on the results of both Bernard et al (2019) and Curry et al (2021). We incorporate movement on three major thrust fault structures including the north‐verging North Pyrenean Fault, south‐verging Axial Zone thrust fault to simulate the Nogueres thrust, and a south‐verging Axial Zone bounding south Pyrenean Thrust to simulate the Orri thrust (Figure 2a).…”

“…To better contextualize the low‐temperature thermochronometry detrital data sets, we incorporate new PECUBE thermokinematic modelling that predicts thermal histories for rock particles advected through a prescribed surface topography (Braun, 2003; Braun et al, 2012). We leveraged orogen‐scale inverse thermokinematic modelling from the Pyrenees (Curry et al, 2021) that incorporates a spatially extensive bedrock multi‐thermochronometer data set and independent surface uplift rates from topographic evolution models (Curry et al, 2019; Huyghe et al, 2012). The kinematics from these topographic evolutions and previous tectonic models are applied in a new PECUBE forward model that incorporates variable exhumation rates and movement on major thrust fault structures that simulate Pyrenean deformation.…”