Research:

My phD background consisted of a multidisciplinary study to establish an absolute chronology of the structuring of the western part of the Alpine arc and the characterisation of the fluids associated with these different deformation phases.

A sampling campaign follows with structural work (orientation of geological layers, identification of faults or C-S structures, measurement of the orientation of veins, etc.) and microstructural work (striations and orientation of calcite fibres). At the sample scale, several thin sections can be studied to represent the different phases and movements that can be recorded. The different generations are identified via cross-cutting criteria in LPNA, LPA or via calcite chemistry in cathodoluminescence and are analysed in LA-IPC-MS in order to construct isochrones. The ages are then interpreted and placed in a more general regional geodynamic context.

In addition to this, I have been able to study mineralizing fluids through the study of stable carbon and oxygen isotopes as well as clumped isotopes. Firstly, the δ¹³C and δ¹⁸O signature of fault calcites can be an indicator of fluid source. From the isotopic signature of the calcite and this crystallisation temperature, thermodynamic models can be used to recalculate the signature of the mineralising fluid and to directly determine its source. This information describes the dynamics of the fluids circulating during the deformation phase, either surface fluids, which can be linked to a precipitation paleoaltitude, or hydrothermal fluids, with indicators of depth or interactions with certain types of rock.

Now at the AGW, I’m in charge of the LA-ICPMS with Pr. Zeh, so feel free to contact me if you have any inquiry about dating or elemental analysis.

Projects:

1) « U-Pb dating of calcitic and dolomitic cements of the Middle Oxfordian Jurassic inner platform ». Project leader: James Richard (Université de Franche-Comté).

The Middle Oxfordian Jurassic inner platform is an important zone of fluid circulation. The carbonate reservoirs in this area have undergone complex diagenesis processes, including the precipitation of calcitic and dolomitic cements (Figure 5) which can significantly affect reservoir quality. The application of the U-Pb dating method to the different generations of cements would provide absolute temporal constraints on porosity closure. These new data would complete the exhumation history of the platform. We also plan to examine the isotopic composition of the cements to assess the origin of the fluids. The results of this study will provide a better understanding of the diagenesis processes in this region, the fluid circulations, their impacts on the reservoir quality and the exhumation history of the area.

2) « Timing and role of inherited structures in the development of transpressive structures in fold and thrust belts: new insights from Jura ». Project leaders: Flavien Choulet (Université de Franche-Comté) & Luca Smeraglia (Université de Rome).

This study uses a multi-disciplinary and multi-scale approach combining fieldwork (Figure 4), stable isotopes (δ¹³C and δ¹⁸O) and U-Pb geochronology on striated fault planes. The main results expected will be: (1) a new updated tectonic model for the development of fold and thrust deformation in the Jura, which takes into account the role of inherited structures, using absolute age constraints for fault movements and (2) a model of groundwater flow in fractured carbonate aquifers of the Jura. In addition, the palaeostresses associated with the fault movement will be calculated in order to define the regional tectonic framework of the structuring of the Jura fold and thrust belt. As the Jura belt is considered as an archetypal fold and thrust belt, the proposed models could be considered as reference tectonic/hydrogeological models in other fold and thrust belts around the world.