Multi-methods characterization of quartz for source-to-sink tracing in alluvial sediment and dosimetry approaches – QUARTZ

In the actual global change context, one of our issues is to constrain geological processes in relation with forcings, including dynamics of climat change, that condition environment and resources of the critical zone. In such a context, alluvial systems constitute very suitable proxies. Indeed, alluvial sediments provide valuable information about the conditions that prevailed at the time of their deposition. They constitute the response of an aggrading system to the climatic, tectonic (paleo)geographic and anthropic contexts of the last millennia. The characterization of sediments in an alluvial system, in particular their source, but also the sedimentary dynamics they reflect, allows to indirectly evaluate these constraints. Within these sediments, quartz has the advantage of being extremely ubiquitous. It is found in a large majority of alluvial systems, is very resistant and slightly affected by alteration, either over time or between upstream and downstream transfer systems, or even during different sedimentary cycles. Finally, quartz is characterized by a composition and a behaviour in front of various stimuli (light, irradiation, ...) which seems related to the initial conditions of formation, but perhaps also to its sedimentary history.
In QUARTZ project, we aim to develop a new methodology of characterization for quartz grains, by using their luminescence and paramagnetic properties together with their composition and repartition in trace elements to use them as markers of sedimentary dynamics. Our approach is based on the unique and innovative combination of reliable characterization and dating methods, such as Optically Stimulated Luminescence (OSL), Electron Spin Resonance (ESR), Cathodoluminescence (CL) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) but also participate in the development of innovative technologies such as Laser Induced Breakdown Spectroscopy (LIBS) in order to achieve a high level of quartz characterization. QUARTZ project intend to demonstrate that each quartz grain has a specific signature of its origin and to determine how this signature evolves over time, along the various sediment recycling. Understanding the variations of quartz grain characteristics within the rivers sediment will help to estimate the variation over time of the alluvial dynamics, including volumes of sediments transported in a Source-to-Sink point of view and indirectly response of the system to external changes.