Speaker: Frances Deegan, Department of Earth Sciences, Uppsala University, Sweden

Large Igneous Provinces (LIPs) whose magma plumbing systems intersect sedimentary basins are linked to upheavals of Earth’s carbon and sulfur cycles, its climate, and life history, yet the underlying mechanistic links remain elusive and are hotly debated. In this seminar, I will present an overview of petrological experiments (1200 °C, 150 MPa, 0 to 600 s run-times) that have been conducted to explore interaction between basaltic melt from the High Arctic LIP and carbonaceous mudstone/shale (0.5% S and 4.7% organic carbon) from the Sverdrup Basin, arctic Canada. The experimental results show that thermal stress and devolatilization causes shale to shatter, which accelerates assimilation by increasing reactive surface area. Shale assimilation therefore triggers sudden release of C-O-H-S volatiles while effectively contaminating the host melt and generating a sulfide xenomelt within the shallow parts of LIP plumbing systems. I will also briefly present experiments replicating sulfate evaporite assimilation using starting materials from the Franklin LIP exposed on Victoria Island, Canada. These magma-evaporite experiments demonstrate effective sulfur mobility in LIP plumbing systems intersecting evaporites and the formation of a locally sulfur-enriched and oxidized contaminated melt. Upscaled to LIP dimensions, magma-shale and magma-evaporite interaction can have implications for paleoclimate changes, extinction events, and the potential resource endowment of LIPs emplaced into volatile-rich sedimentary sequences.

Experimenting with melts and sediments from large igneous provincesSills emplaced into shales on Ellesmere Island, Canadian Arctic Islands (High Arctic Large Igeneous Province)Photo: Frances Deegan

IGV Seminar Series organizers
Wei-Li Hong, wei-li.hong@geo.su.se
Paola Manzotti, paola.manzotti@geo.su.se
Christian Stranne, christian.stranne@geo.su.se