Hg (mercury) is a toxic and highly volatile metal element. Because one of the two major sources of Hg in the atmosphere is volcanic degassing, its accumulation in sediments is used to link major Phanerozoic and Precambrian climatic changes to massive volcanic events. However, while the behavior of mercury in sedimentary systems is gaining interest and becoming well understood, the source of Hg in volcanic systems before degassing remains vague. Analytical challenges linked to this element, such as sample preparation and/or analyses, make such uncertainty even worse. Indeed, the few studies investigating Hg in magmatic systems appear to have unintentionally under or overestimated the concentration of Hg in magmatic rocks because of these unforeseen challenges.  

Project STECALMY seeks to investigate the source and mobility of Hg in the Earth’s crust by investigating the Sesia Magmatic System (SMS; Western Southern Alps, Italy), an exposed continental magmatic system that can be traced from its deepest roots to its volcanic products. Here we will design a rigorous sample preparation and analytical procedure to optimize Hg analyses in crystalline rocks. After, we will analyze Hg in carefully selected rocks of the SMS, from uncontaminated and undegassed magmatic rocks to metamorphic rocks in which they emplaced and to the volcanics erupted to the surface. For these magmas, Hg gain and loss during crustal assimilation, crystallization, and degassing in continental settings will be strengthened by combining petrography, elemental, and isotopic geochemistry. Project STECALMY will produce the first methodologically robust model on the source and mobility of Hg within a continental magmatic system.

Project: 101066580 — STECALMY — HORIZON-MSCA-2021-PF-01 is founded by EUROPEAN RESEARCH EXECUTIVE AGENCY (REA) – Marie Skłodowska-Curie Actions & Support to Experts A.2 – MSCA European Postdoctoral Fellowships.