In geology, field work is a vital component in the exploration of geological materials including rocks and minerals. This allows geologists to study the history of the Earth, predict natural disasters, and optimize the extraction of natural resources.
Renelle Dubosq, a recent PhD graduate who worked with Professor David Schneider, utilized field work and state-of-the-art high spatial resolution microscopy throughout her PhD to study physico-chemical processes in minerals and the effect on their mechanical properties. The objective was to link nanoscale structural and chemical observations to larger tectonic-scale processes on Earth. Her findings can be separated into three major chapters, which fall within several subdisciplines of geosciences: economic geology, structural geology, geochemistry, and volcanology.
Economic geology includes the study of the formation of mineral deposits. In her first chapter, Renelle examined how the deformation of sulphide minerals, in the context of metallic ore deposits, can influence the mobility of trace metals such as gold and silver. Her results contradicted pre-existing models that suggested the deformation of sulphides led to metals being mobilised out of the minerals. Instead, her results unveiled that the deformation of sulphides was creating nano-scale traps and therefore enhancing the concentration of these metals within mineral structures. With increasing demands for base- and precious metals, these results will lead to more refined exploration methods to find additional economically viable deposits.
Next, Renelle focused on understanding how fluids present within minerals can impact their deformational behaviour. According to existing literature, fluids typically have a weakening effect on rocks and minerals. On the contrary, Renelle’s findings revealed processes where fluids, in the form of nano-scale inclusions, can instead have a hardening effect on the mineral. Such findings help deepen our understanding of the deformational behaviours of geological materials in fluid-rich environments and thus larger mass transfer processes on Earth.
Lastly, Renelle studied gas bubble nucleation processes in magmas by conducting a nanoscale analysis on a synthetic volcanic glass. Her research revealed that bubbles do indeed nucleate on element clusters in volcanic melts, but the clusters are so small that they cannot be seen with the naked eye. This observation will help understand the processes that control the eruptive style of volcanoes.
Renelle won the 2022 Geological Association of Canada Tectonics Group 2022 Jack Henderson Award for best PhD thesis and the 2022 uOttawa Governor General’s Gold Medal for outstanding PhD thesis in science and engineering. She is currently the only geologist as a postdoctoral fellow at the Max-Planck-Institut für Eisenforschung in Germany, where she is pursuing interdisciplinary research building bridges between materials science and Earth science.
Outside the lab, Renelle participated in outreach activities including the national Let’s Talk Science program and the Girls and Women in Science seminars, where she shared her passion for geology. Renelle hopes to be a role model for other women and Indigenous people aiming to pursue a career in STEM.