En poursuivant votre navigation sur ce site, vous acceptez le dépôt de cookies dans votre navigateur. (En savoir plus)

Doctoral contract : Post-glacial geomorphic and erosion response in the western European Alps and Pyrenees (W/M)

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : vendredi 29 octobre 2021

Assurez-vous que votre profil candidat soit correctement renseigné avant de postuler. Les informations de votre profil complètent celles associées à chaque candidature. Afin d’augmenter votre visibilité sur notre Portail Emploi et ainsi permettre aux recruteurs de consulter votre profil candidat, vous avez la possibilité de déposer votre CV dans notre CVThèque en un clic !

Faites connaître cette offre !

General information

Reference : UMR5275-FABCAR-051
Workplace : GRENOBLE
Date of publication : Friday, October 8, 2021
Scientific Responsible name : VALLA Pierre
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 February 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

Quantifying landscape dynamics has proven problematic in the context of current climate change because geomorphic processes operate at interrelated timescales. Alpine landscapes were progressively shaped during the Quaternary under oscillating glacial-interglacial conditions, but the net impact of glaciation on mountains is spatially variable. Furthermore, modern mountain erosion integrates both (1) the long-term response (i.e. 1-10 kyr) to glacial retreat and glacial conditioning of topography, and (2) the recent impact of climate change (i.e. 10-100 yr) as a result of glacier shrinking and permafrost thawing. Predictions of the geomorphic response to future climatic scenarios have consequently remained limited. All these observations point toward the need for a better assessment of mountain landscape sensitivity to climate forcing over a range of timescales. In this PhD project, we aim at investigating the geomorphological record in two natural settings (western European Alps and Pyrenees) to quantify postglacial erosion processes and sediment transfer since the Last Glacial Maximum (LGM, ca. 20 ka), addressing the following question: what are the interactions, threshold effects and response times between climate change, glacier retreat and erosion processes in alpine settings since the LGM?

Work Context

ISTerre is an institute focused on the different domains of Earth Sciences (geophysics, geology, geochemistry). It gathers 290 permanent and short-term staff between sites of Grenoble and Chambery, and is one of the biggest French institutes in the Geosciences field. The PhD student will be part of the "Tectonics, Reliefs, Basins" (TRB) team which is composed of around twenty researchers and ten PhD students/postdocs.
The doctoral project is financially supported by the ANR-PIA MAGICLIM project ("MountAin Glacier fluctuations and landscape dynamIcs under a changing CLIMate" - PI P. Valla) which will cover all financial expenses for fieldwork missions, analyses and planned travels (collaborations and conferences) within the framework of the PhD project. The PhD student will also be part of the MOPGA program (https://makeourplanetgreatagain-cnrs.com/) and will participate to associated conferences/workshops.
The overall objectives of this project are to (1) quantify the spatial (western Alps vs. Pyrenees) and temporal (since the LGM to late Holocene) variability in mountain erosion rates using catchment-wide denudation data, (2) understand and trace sediment production and transfer during lateglacial to postglacial timescales, with potential source changes over time, and finally (3) better understand how geomorphic agents and timescales interact to regulate the landscape response to a changing climate and associated glacier retreat. To achieve these different objectives, the PhD project will be organized around a multi-method approach. First, the PhD student will use in-situ cosmogenic nuclides (10Be quartz) in modern river sands, targeting different catchments in the Pyrenees to complement existing datasets. This work will allow to establish a database for the Pyrenees for geomorphic comparison with the western European Alps. In addition, the PhD student will acquire new in-situ cosmogenic nuclide data (10Be/26Al, potentially 14C) in Lateglacial and Holocene sediment archives (lacustrine and floodplain deposits, floodplain and alluvial fan) as tracer for paleo-erosion or paleoenvironmental conditions. Sediment provenance will also be investigated using mineralogical and geochemical analyses together with detrital thermochronology to quantify temporal changes in river-sediment sources since the LGM. Sediment transfer times will finally be evaluated for lateglacial to postglacial deposits with bulk sediment geochemistry to derive weathering indices and U-Th series to date the time of sediment production (i.e. the comminution age) and infer the budget contribution of re-mobilized glacial sediments during the Lateglacial/Holocene as well as to evidence complex sediment transfer. Ultimately, the PhD student will work on surface-process modeling using the state-of-the art Landlab model which predicts landscape evolution and sediment production (river and hillslope processes) under climate forcing. We will focus on the influence of rainfall variability on stochastic river processes and landslide triggering, and on other potential factors driving the geomorphic response to glacial/interglacial transition (topographic pre-conditionnig, stored subglacial sediments, tectonic/isostatic uplift etc.).
The PhD candidate should have knowledge in quantitative geomorphology, Quaternary geology and/or sedimentary geochemistry. Some skills in topographic analysis, GIS mapping and numerical modeling would be advantageous to lead this project and establish planned collaborations. Applicants should have a MSc degree in geology, geophysics, geography, or any related quantitative discipline in natural sciences, with strong interests in earth surface dynamics. Successful applicants should have strong written and oral communication skills in English (French skills can be advantageous).
The doctoral team is composed by Pierre Valla (ISTerre, CNRS-Univ. Grenoble Alpes) and several close collaborations at ISTerre and national institutes (Edytem Chambery, EVS Lyon, HNHP Perpignan, Geosciences Rennes). International collaborations will be also established within the doctoral project (Univ. Lausanne – Suisse, Univ. Wollogong – Australie).

We talk about it on Twitter!