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Post‐orogenic evolution of the southern P yrenees: constraints from inverse thermo‐kinematic modelling of low‐temperature thermochronology data
Author(s) -
Fillon Charlotte,
van der Beek Peter
Publication year - 2012
Publication title -
basin research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.522
H-Index - 83
eISSN - 1365-2117
pISSN - 0950-091X
DOI - 10.1111/j.1365-2117.2011.00533.x
Subject(s) - foreland basin , geology , thermochronology , inversion (geology) , tectonics , structural basin , paleontology , geomorphology
The late‐stage evolution of the southern central P yrenees has been well documented but controversies remain concerning potential N eogene acceleration of exhumation rates and the influence of tectonic and/or climatic processes. A popular model suggests that the P yrenees and their southern foreland were buried below a thick succession of conglomerates during the O ligocene, when the basin was endorheic. However, both the amount of post‐orogenic fill and the timing of re‐excavation remain controversial. We address this question by revisiting extensive thermochronological datasets of the A xial Z one. We use an inverse approach that couples the thermo‐kinematic model P ecube and the N eighbourhood inversion algorithm to constrain the history of exhumation and topographic changes since 40 Ma. By comparison with independent geological data, we identified a most probable scenario involving rapid exhumation (>2.5 km Myr −1 ) between 37 and 30 Ma followed by a strong decrease to very slow rates (0.02 km Myr −1 ) that remain constant until the present. Therefore, the inversion does not require a previously inferred P liocene acceleration in regional exhumation rates. A clear topographic signal emerges, however: the topography has to be infilled by conglomerates to an elevation of 2.6 km between 40 and 29 Ma and then to remain stable until ca . 9 Ma. We interpret the last stage of the topographic history as recording major incision of the southern P yrenean wedge, due to the Ebro basin connection to the M editerranean, well before previously suggested M essinian ages. These results thus demonstrate temporally varying controls of different processes on exhumation: rapid rock uplift in an active orogen during late E ocene, whereas base‐level changes in the foreland basin control the post‐orogenic evolution of topography and exhumation in the central P yrenees. In contrast, climate changes appear to play a lesser role in the post‐orogenic topographic and erosional evolution of this mountain belt.