Lawrence Percival, Oxford University
Deep time climate/extinction events and their relationships with large scale volcanism
Monday, 5 June 2017, 15.00 in Node Room 074/02
Earth’s history has featured a number of mass extinctions and other major environmental perturbations such as Ocean Anoxic Events (OAEs). The ages of many of these events have been ascertained as broadly the same as volcanic rocks that make up Large Igneous Provinces (LIPs), which record the geologically abrupt emplacement of millions of cubic kilometres of magma. Because of the broad coincidence between LIPs and major climate/extinction events, and the impact of volcanic activity upon the modern climate, a causal relationship between the two has been suggested. Mercury is emitted in the modern as a trace volcanic gas, and has a residence time of 1–2 years in the atmosphere, allowing it to be globally distributed before it is rained out and deposited to sediments. Thus it has potential as a direct marker of volcanic activity in the sedimentary record. Here I demonstrate how mercury has been used to further our understanding of the role volcanism may have played in one of the largest extinctions of animal life (the end-Triassic mass extinction 201.5 million years ago), and another episode of major environmental change (the Toarcian OAE 183 million years ago). Our work shows that mercury can be used successfully as an indicator for volcanism from a number of LIPs associated with extinctions and/or climate events, and also combined in multiproxy studies as a powerful tool for investigating the mechanisms that led from large scale volcanism to environmental and biospheric stress.
Please get in touch with Jessica Whiteside if you would like to talk to Lawrence.