Jessica UZEL

Morphotectonic evolution of the Pyrenan range during the post-compressive period: weathering and dismantling of an uplifting planation surface

Supervisors:
Yves Lagabrielle – Université de Rennes 1
Robert Wyns – BRGM, Orléans, France

Major Results

This study has contributed to the depiction of the Pyrenean planation surface on two main points: (i) it has confirmed that it formed below the present-day elevation of its remnants and was subsequently uplifted, and (ii) the Cretaceous 40Ar/39Ar ages of weathering have indicated that some Pyrenean low relief surfaces may be remnants of pre-orogenic surfaces.

Abstract

The aim of this PhD was to provide new insights into the evolution of an extensive Planation Surface (PS) in the collisional Pyrenean Range. This PS, today dissected due to tectonic, fluvial and glacial processes, is identified through remnants of low relief surfaces lying at high elevation in the range and was ascribed to the late- to post-collisional period (late Oligocene – late Miocene). The unique feature of those PhD works was to use weathering profiles associated with the Pyrenean PS remnants to provide new indicators as to their age(s) of formation. I performed 40Ar/39Ar dating on supergene K-Mn oxides grains collected from samples lying on PS remnants. Two weathering periods were obtained: (i) Aptian-Campanian (ca. 110 – 80 Ma), which indicates that some low relief surfaces in the Pyrenees may be remnants of pre-orogenic surfaces, and (ii) Pleistocene (ca. 1 Ma) ages.

 

The unexpected lack of Mio-Pliocene ages (a period thought to be prone to weathering, characterized by a subtropical climate in the Pyrenean post-collisional period) was interpreted as a reactivation of weathering profiles, which is fostered in continental areas subject to slow uplift. I also performed a geomorphological analysis of the dismantling of the Pyrenean PS, focused on Miocene to present-day fluvial incisions in the Western Pyrenees which demonstrated that successive incisions occurred between Langhian and Pliocene, most likely as a result of successive post-collisional uplift events (Uzel et al., 2020). The Pyrenean PS thus formed below the present-day elevation of its remnants. A broader-scale analysis of the repartition of uplift evidence in time and space at the Western European scale from Miocene onwards suggested a dominant influence of far-field effects from the active Eurasian and Iberian plates borders during the Miocene – present-day period.

Geomorphological analysis of the dismantling of the PS with a special focus on the Aspe catchment

Fluvial incisions in the North-Western Pyrenees (Aspe Valley): dissection of a former planation surface and some tectonic implications.

Fluvial incisions in the North-Western Pyrenees (Aspe Valley): dissection of a former planation surface and some tectonic implications.

Uzel, J., Nivière, B., Lagabrielle, Y. (2020). Fluvial incisions in the North-Western Pyrenees (Aspe Valley): dissection of a former planation surface and some tectonic implications. Terra Nova, 32, 11-22. DOI: 10.1111/ter.12431

keywords:  Erosion, HYDROLOGY, Geomorphology: general, Tectonics and landscape evolution, TECTONOPHYSICS, Tectonics and climatic interactions

DOI: https://doi.org/10.1111/ter.12431 

Mantle exhumation at magma-poor passive continental margins. Part II: Tectonic and metasomatic evolution of large-displacement detachment faults preserved in a fossil distal margin domain (Saraillé lherzolites, northwestern Pyrenees, France)

Mantle exhumation at magma-poor passive continental margins. Part II: Tectonic and metasomatic evolution of large-displacement detachment faults preserved in a fossil distal margin domain (Saraillé lherzolites, northwestern Pyrenees, France)

Lagabrielle, Y., Asti, R., Fourcade, S., Corre, B., Labaume, P., Uzel, J., … & Picazo, S. (2019). Mantle exhumation at magma-poor passive continental margins. Part II: Tectonic and metasomatic evolution of large-displacement detachment faults preserved in a fossil distal margin domain (Saraillé lherzolites, northwestern Pyrenees, France). Bulletin de la Société Géologique de France, 190(1).

keywords:  North Pyrenean Zone, Saraillé, mantle exhumation, fluid-rock interactions, talc-chlorite schists, greenschist facies, detachment faults, mid-Late Cretaceous

DOI: https://doi.org/10.1051/bsgf/2019013

Mantle exhumation at magma-poor passive continental margins. Part I. 3D architecture and metasomatic evolution of a fossil exhumed mantle domain (Urdach lherzolite, north-western Pyrenees, France)  

Mantle exhumation at magma-poor passive continental margins. Part I. 3D architecture and metasomatic evolution of a fossil exhumed mantle domain (Urdach lherzolite, north-western Pyrenees, France)

Lagabrielle, Y., Asti, R., Fourcade, S., Corre, B., Labaume, P., Uzel, J., … & Picazo, S. (2019) Mantle exhumation at magma-poor passive continental margins. Part I. 3D architecture and metasomatic evolution of a fossil exhumed mantle domain (Urdach lherzolite, north-western Pyrenees, France) ; BSGF Earth Sciences Bulletin 2019, 190, 8

keywords:  North Pyrenean Zone, Urdach, mantle exhumation, fluid-rock interactions, listvenites, greenschist facies, detachment faults, Late Cretaceous

DOI: https://dx.doi.org/10.1051/bsgf/2019007

PhD Thesis: Evolution morphotectonique post-compressive de la chaîne des Pyrénées : altération et démantèlement d’une surface d’aplanissement en cours de soulèvement

PhD Thesis: Evolution morphotectonique post-compressive de la chaîne des Pyrénées : altération et démantèlement d’une surface d’aplanissement en cours de soulèvement

Jessic Uzel. Evolution morphotectonique post-compressive de la chaîne des Pyrénées : altération et démantèlement d’une surface d’aplanissement en cours de soulèvement. Université de Rennes 1, 2019

keywords: Planation surface, Subtractive weathering, Ar/Ar dating, Tectonic geomorphology, InSAR, Pyrenees

DOI: https://ged.univ-rennes1.fr/nuxeo/site/esupversions/8ec2bf0a-f475-4dce-83cc-88c8e018da2a?inline