Dr. Jean-Guillaume Feignon

Education

• 2017–2022 PhD in Natural Sciences, speciality: Earth Sciences, Department of Lithospheric Research, University of Vienna (Austria).
• 2013–2015 Master (M.Sc.) in Earth Sciences, speciality: Volcanology, Laboratoire Magmas et Volcans, Blaise Pascal University, Clermont-Ferrand (France).
• 2010–2013 Bachelor (B.Sc.) in Earth Sciences, Blaise Pascal University, Clermont-Ferrand (France).

Research Topics

My research is focused on the study of the petrography and the geochemistry of volcanic rocks, as well as impactites (rocks formed or affected following a meteorite impact event). During my master, I worked on the identification, characterization and dating (δ¹⁸O)  of tephra layers in a drill core recovered offshore La Réunion island (France), in order to refine the volcanic history of the Piton des Neiges volcano. I also worked on the characterization and analysis of pyroclastic deposits and melt inclusions in minerals from an explosive, andesitic eruption of the Mocho-Choshuenco volcano (Chile), in order to explain the strong explosive behaviour of this eruption. Pre-eruptive volatile contents (H₂O, CO₂) were measured within the melt inclusions, and revealed unusual, very high contents in CO₂ in the magma of this eruption. My PhD worked focused on the characterization (petrography, geochemistry, and shock metamorphism) of the impactites from the Chicxulub impact structure peak ring (Yucatán peninsula, Mexico), recovered by the IODP-ICDP Expedition 364 drilling. I mainly realized the characterization of shock metamorphic features in quartz grains and other minerals from the granite unit, and shocked pressure estimates; the geochemical characterization of the granite unit from the peak ring (sources and alteration); and the search for an impactor contamination within the Chicxulub peak ring impact melt rocks to better understand the fate of the projectile during the impact. I was also awarded the Barringer family fund for meteorite impact research in 2019, for a field work in Gabon in order to identify a potential meteorite impact structure.

My research uses an approach combining a wide range of routine and high-precision petrographic and geochemical techniques, such as, optical microscopy, universal stage (U-stage), Raman spectroscopy (including 3D chemical mapping), scanning electron microscopy (MEB), electron microprobe, micro-X-ray fluorescence analysis, X-ray fluorescence analysis, instrumental neutron activation analysis (INAA), secondary ion mass spectrometry (SIMS) for measuring H₂O and CO₂contents in melt inclusions, mass spectrometry (ICPMS and TIMS) for highly siderophile element (HSE) contents, and Sr–Nd, and Re–Os isotopes analysis.

My current project focus on the use of volcanological analogue in order to better understand the aggregation processes (formation of accretionary lapilli) occurring in the ash plumes produced by large impact events, and their potential effect(s) on the terrestrial climate.

In addition, my research includes a field work part, in order to recover rock samples, identify new impact structures, and also document volcanic eruptions occurring all around the world. Dissemination of my research is made through publications in peer-reviewed journals, scientific conferences, interviews (e.g., radio/press), and also lectures and field trip in the framework of the European Volcanological Association (L.A.V.E.).