High-resolution InSAR mapping of the post-orogenic Pyrenean vertical displacement rates
Abstract
Post-orogeny is commonly thought as a phase of relief destruction consequently to the transition from a horizontal forces-dominated to an erosional processes-dominated state. In the Pyrenean range, Western Europe, Late Miocene post-orogenic exhumation measured by low-temperature thermochronology consolidates the idea that substantial uplift and erosion are coeval with topographic stability, despite the very low convergence rate. At present-day, the question remains, as the sparse GPS coverage is insufficient to discuss the range's vertical motion and the driving mechanism of vertical forces. Such information is also key to characterize the localized and continuous seismic activity observed in the Western-Central Pyrenees.
We constrained the present-day velocity field of the Western-Central Pyrenees from 2015 to 2018 using high-density INterferometric Synthetic-Aperture Radar (InSAR) measurements. A data stack of 156 SAR interferograms is computed using C-band images acquired by the Sentinel-1A and Sentinel-1B satellites, both in the ascending and descending modes. The accuracy of these measurements allows us to map and quantify for the first time the low present-day vertical motions of the Central-Western Pyrenees, and reveals substantial post-orogenic uplift rates, from 0.7 to 3mm/year. The observed vertical velocity field points out the partitioning of the vertical motions in the Pyrenees, which closely match the Pyrenean structural architecture from lithospheric imaging and as such highlights the importance of crustal inheritances and architecture in the post-orogenic evolution. Detailed analysis of the vertical displacement rates combined with topography, seismicity and Bouguer anomaly, stresses that these crustal inheritances, together with the present-day differential vertical motions resulting from isostatic processes, are one of the driving forces of the seismicity anomaly in the Pyrenees.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP21A..07B
- Keywords:
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- 1815 Erosion;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS;
- 8177 Tectonics and climatic interactions;
- TECTONOPHYSICS