Missions

- characterize the complex, multi-phase structural evolution of the Dévoluy massif
- proceed with the unfolding and balancing of the structures and propose an evolution model enabling us to validate a geometric model for the present with a minimum of uncertainty.

Activités

The Dévoluy massif consists mainly of folded carbonate sedimentary formations of Jurassic to Cretaceous age. The structural data required for modeling will be derived from existing and new mapping data acquired during surface field missions, as well as from cave exploration with the help of speleological teams working on the massif (collecting as much data as possible on the dips of geological strata and measurements of fault orientations and plunges). The reconstruction of the geometry and 3D evolution of the basin, using Move structural modeling and analysis software (academic license provided to UCA by Petroleum Expert), will be calibrated on the basis of these structural data. We will also take drone images of the massif to characterize surface structures. Structural modeling will be carried out in 3 stages:
- Construction of 2D serial cross-sections. These sections will be constructed using standard geometric techniques of balanced and restored (unfolded) sections to obtain a pre-deformation state, using the flexural-slip method. Restoration is used to calculate shortening rates and obtain the geometry of strata prior to deformation.
- Using cross-sections and outcrop data to build a 3D geological model. Lines (in cross-sections) and outcrop limits of sedimentary formations and faults (previously digitized in 3D on DTM) will be interpolated with a triangular mesh.
- Validation of cross-sections and 3D model through restoration. This restoration will integrate Raman paleothermicity data to better constrain rock burial, exhumation and reservoir paleotemperatures (collaboration with A. Lahfid from BRGM).
This project should therefore not only enable us to specify the 3D architecture of the deep-seated structural system and its kinematics of formation, but also to assess the consequences for the geometry and distribution of deep-seated aquifers, and hence for the circulation of water in the basin. This development may involve setting up the tools needed to draw up a risk map, with a view to better targeting priority management actions in the long term. The deliverables of this project will be
- a 3D model of the Dévoluy massif for hydrogeological modeling;
- a report and a seminar to present the results;
- a peer-reviewed scientific publication.

Compétences

- Thrust tectonics
- Structural geology
- 3D modeling and balancing of geological structures
- Fieldwork
- MOVE software
- Fluency in French and English
- Ability to adapt, organize and plan
- Team spirit and initiative

Contexte de travail

Characterization of the 3D structural architecture of the Dévoluy massif (Western French Alps) using structural modeling is an essential step for understand the structure of karstic flows and the location of potential flooded zones. Few recent, accurate structural models have been proposed to characterize the complex, multi-phase structural evolution of the Dévoluy massif. The geological cross-sections already constructed in this area have only been drawn schematically, and do not incorporate the precise geometry of deformed strata and faults, so that we can proceed with the unfolding and balancing of the structures and propose an evolution model enabling us to validate a geometric model for the present with a minimum of uncertainty.
This project will be led by a researcher supported by research teams from the Côte d'Azur University-Géoazur, CEREGE, BRGM and speleologists working on the massif to identify deep structures.

The proposed research position is part of a collaborative project between Côte d'Azur University-Géoazur and Agence de l'Eau RMC to study the 3D structure of the Dévoluy hydrogeological massif in the Western Alps.
The person employed will work in the Géoazur laboratory, UMR7329, at the Valbonne site (06). The Géoazur laboratory is a multi-disciplinary joint research unit under national (CNRS and IRD) and local (Côte d'Azur University and Côte d'Azur Observatory) supervision. It comprises geologists, geophysicists and astronomers working together on major scientific themes such as hazards (seismic, gravitational, tsunamigenic, hydro-climatic, chemical) and their associated risks, lithospheric dynamics and Earth imaging, geodesy-metrology of the Earth and the near Universe.
The laboratory employs around one hundred permanent staff (researchers, teacher-researchers, ITAs) and between 70 and 110 non-permanent staff (PhD students, post-docs, ATERs, interns, visiting researchers). It is spread over 2 sites: the Azur-CNRS campus at Sophia Antipolis (Valbonne) and the Calern - Caussols site of the Côte d'Azur Observatory.
The person employed will join the laboratory's GEOMAT team, and will also work closely with French partners CEREGE and BRGM.

Contraintes et risques

High mountain terrain and caving