Doctoral Contract : Post-Glacial Geomorphic And Erosion Response In The Western European Alps And...

Universities and Institutes of France

France

October 29, 2021

Description

  • Organisation/Company: CNRS
  • Research Field: Astronomy Environmental science Geosciences
  • Researcher Profile: First Stage Researcher (R1)
  • Application Deadline: 29/10/2021 23:59 - Europe/Brussels
  • Location: France › GRENOBLE
  • Type Of Contract: Temporary
  • Job Status: Full-time
  • Hours Per Week: 35
  • Offer Starting Date: 01/02/2022
  • 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).

    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?

    Web site for additional job details

    https: // emploi.cnrs.fr/Offres/Doctorant/UMR5275-FABCAR-051/Default.aspx

    Required Research Experiences
  • RESEARCH FIELD
  • Geosciences

  • YEARS OF RESEARCH EXPERIENCE
  • None

  • RESEARCH FIELD
  • Astronomy

  • YEARS OF RESEARCH EXPERIENCE
  • None

  • RESEARCH FIELD
  • Environmental science

  • YEARS OF RESEARCH EXPERIENCE
  • None

    Offer Requirements
  • REQUIRED EDUCATION LEVEL
  • Geosciences: Master Degree or equivalent

    Astronomy: Master Degree or equivalent

    Environmental science: Master Degree or equivalent

  • REQUIRED LANGUAGES
  • FRENCH: Basic

    Contact Information
  • Organisation/Company: CNRS
  • Department: Institut des sciences de la Terre
  • Organisation Type: Public Research Institution
  • Website: https:// isterre.fr/
  • Country: France
  • City: GRENOBLE