Rock uplift and erosion rate history of the Bergell intrusion from the inversion of low temperature thermochronometric data

Abstract

The Bergell intrusion (European Alps) was one of the first locations where thermochronometry was used to resolve changes in erosion rate, yet, relating these changes to variations in climate or in local tectonics remains challenging. One approach that enables changes in erosion rate to be related to changes in climate or rock uplift rate is to utilize landscape evolution models, as topographic response to these forcing parameters is unique. Furthermore, low temperature thermochronometric systems have the potential to resolve topography through time and thus topographic response. We present new (U-Th)/He data for samples collected across 2 km of relief from the Bergell. The ages range from $2 to $16 Ma and define an age elevation with an apparent exhumation rate of 0.1 km/Myr. In order to infer erosion rates, we use a thermokinematic model to solve the heat equation in the crust, track material points through time and predict thermochronometric data. Paleo-topography and erosion rate are parameterized using the stream power model. We find that rock uplift rates were 0.4 km/Myr from $25 to $20 Ma and subsequently decreased to 0.05 km/Myr. This results in a gradual decrease in erosion rate from rates of 0.4 to 0.1 km/Myr. A recent increase in rock uplift rate at $4 Ma to $0.6 km/Myr is required to explain the youngest ages and high topographic relief.

Constant denudation rates in a high alpine catchment for the last 6 kyrs

“…Nonetheless in cases such as the Fedoz, catchment intermittent storage does not result in a significant increase in 10 Be concentrations during transport and is not contradicting the 'let nature do the averaging' effect. Therefore, the buffered 10 Be signal is argued to be robustly representative as a long term (kyr) background denudation rate of 0.72 AE 0.14 mm/yr for the entire Fedoz catchment, which is typical for the Central Alps (Wittmann et al, 2007), Eastern Alps (Norton et al, 2011) and comparable with long term (Myr) exhumation rates of the adjacent Bergell massif (Fox et al, 2014) and Aar massif (Vernon et al, 2009).…”

A Fourier approach for estimating and correcting the topographic perturbation of low-temperature thermochronological data

“…In addition, the implementation of both approaches is hampered by the fact that topography and age-elevation profiles are generally complex, making straightforward estimations of the theoretical Δage topo difficult. To solve this problem we use Fourier analysis (Fourier, 1822) to decompose topography into a set of sinusoidal functions and calculate the summed perturbation for each function (e.g. Fox et al, 2014b;Wang and Zhou, 2009).…”

“…The code predicts thermochronological data from modelled tT-paths, and combined with a neighbourhood algorithm inversion (Sambridge, 1999a,b), enables to efficiently search and estimate exhumation rates and relief evolution (e.g. Braun and Robert, 2005;Braun et al, 2012;Fox et al, 2014a;Glotzbach et al, 2011;Herman et al, 2007Herman et al, , 2009Herman et al, , 2010Reverman et al, 2012;Valla et al, 2010Valla et al, , 2011a.…”

Multicore Parallel Tempering Bayeslands for Basin and Landscape Evolution

“…Fox et al. () reviewed uplift and erosion rate history of the Bergell intrusion from the inversion of low temperature thermochronometric data, and Goren et al. () focused on distinguishing tectonics from fluvial topography using formal linear inversion with applications to the Inyo Mountains, California.…”

“…Initial work was done by Roberts and White (2010), who used Monte Carlo inverse modeling of river profiles to estimate uplift rate histories using African examples. Fox et al (2014) reviewed uplift and erosion rate history of the Bergell intrusion from the inversion of low temperature thermochronometric data, and Goren et al (2014) focused on distinguishing tectonics from fluvial topography using formal linear inversion with applications to the Inyo Mountains, California. Fox et al (2015) investigated the rate of Andean Plateau uplift using reversible jump Markov chain Monte Carlo (MCMC) inversion of river profiles.…”