Dr Simon Stephenson will deliver the ESE Departmental Seminar on the 5th of October 2023: “Destruction and regrowth of lithospheric mantle beneath large igneous provinces”.
Join us in room G41 – RSM Building – on Thursday 5th of October 2023 at 12h00.
Abstract
Large igneous provinces (LIPs) are formed by enormous (i.e., frequently >106 km3) but short-lived magmatic events that have profound effects upon global geodynamic, tectonic, and environmental processes. Lithospheric structure is known to modulate mantle melting, yet its evolution during and after such dramatic periods of magmatism is poorly constrained. Using geochemical and seismological observations, we find that magmatism is associated with thin (i.e., ≲80 km) lithosphere and we reveal a striking positive correlation between the thickness of modern-day lithosphere beneath LIPs and time since eruption. Oceanic lithosphere rethickens to 125 km, while continental regions reach >190 km. Our results point to systematic destruction and subsequent regrowth of lithospheric mantle during and after LIP emplacement and recratonization of the continents following eruption. These insights have implications for the stability, age, and composition of ancient, thick, and chemically distinct lithospheric roots, the distribution of economic resources, and emissions of chemical species that force catastrophic environmental change.
About the speaker
Simon Stephenson is a Postdoctoral Research Fellow at the University of Oxford and Stipendiary Lecturer at University College. He focuses on understanding the impact of mantle processes on the surface using a range of geological and geophysical observations. His current work focuses on constraining the thermal and compositional structure of the asthenospheric and lithospheric mantle in space and time using a range of topographic, geochemical and seismological data with a particular interest in controls on the distribution of mineral resources. His work has addressed a wide range of topics including the influence of mantle convective processes on the heights of sea-level markers and the mantle controls on the composition and spatial distribution of intraplate magmatism.