Revealing hidden volcanic triggers for global environmental change events in Earth’s geological past using mercury (Hg)

Rapid global change events such as mass extinctions punctuate Earth’s geological history. These have driven life’s evolution, shaping the world today. However, the exact processes that trigger or modulate them remain enigmatic. Episodes of large-scale volcanism, namely large igneous provinces (LIPs), are a prime contender. A major obstacle to unravelling the role of LIPs in rapid global change has been lack of a direct/unique proxy for volcanism in the sediments that record events. Without one, determining LIP occurrence and exact temporal relations is challenging, especially where the rock record of LIPs is incomplete. Recent studies have revealed the huge promise of mercury (Hg) as a marker of large-scale volcanism. However, while Hg-record acquisition is gaining pace, we still lack the vital process understanding of the proxy needed to realize its full potential. V-ECHO will test the overarching hypothesis: widespread mercury ‘spikes’ in the geological record are definitive evidence of LIP volcanism even in the absence of coeval lavas.V-ECHO will take an integrated and interdisciplinary approach to develop a process understanding of LIP perturbations to the global Hg cycle and how these translate into sedimentary records. It will address key questions on Hg sources (emission from magmas or thermal metamorphism of intruded rocks) and sinks (deposition pathways and sedimentary preservation). It will combine new measurements with novel experimental techniques and explore key differences in the global Hg cycle deep in Earth’s past. V-ECHO will test whether we can ‘sniff out’ the sedimentary echoes of lost LIPs, especially in the Palaeozoic and Neoproterozoic where the LIP record becomes ever sparser. It will explore proposed volcanic triggers for major Earth change events (e.g., oceanic anoxic events, ‘snowball Earths’) in unprecedented ways. V-ECHO promises a step-change in understanding of environmental impacts of LIP volcanism throughout Earth history.