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Does the kiss of a LIP ever linger for long?

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There is long-standing correlation between Large Igneous Provinces (LIPs) and major mass extinction events in the Geological Record. This is postulated to be due to the emission of large quantities of volcanic gases over a geologically short period of time, causing major climatic perturbations within the Earth system. However tying down a causative mechanism is difficult because the timescales over which volcanic gases operate in the atmosphere are short relative to our precision in dating. I will present data on the eruptive timescales of two contrasting LIPs of similar size: the well known 65Ma Deccan flood basalt province of India, and the 135Ma Paraná – Etendeka volcanic province of Brazil and Namibia. The Deccan traps has been linked to the end-Cretaceous mass extinction, and I will present a magnetostratigraphic chronology that illustrates the difficulty of nailing down an eruptive timescale. Nevertheless the bulk of the magmatism seems to have taken place in 1 Mkm3) comparable to other LIPs associated with mass extinctions, such as the Siberian or Deccan traps. I will present a new magnetostratigraphic chronology for this LIP that suggests that the Paraná – Etendeka volcanic province was emplaced over longer timescales than other LIPs, and / or emitted a lower concentration of volatiles, directly or indirectly during its emplacement. Our new chronology reveals a minimum period of volcanic activity in excess of 4 Myrs suggesting that the anomalously feeble environmental impact of Paraná – Etendeka volcanism may be due to lower effusion rates reducing the atmospheric loading due to volcanogenic volatiles.

This talk is part of the Sedgwick Club talks series.

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