Research Seminar: Tracing magmatic degassing timescales Event as iCalendar

(Science Event Tags)

07 February 2017

10 - 11am

Venue: 303-B05

Location: Princes St

Contact info: Dr Jan Lindsay

Contact email: j.lindsay@auckland.ac.nz

Dr Lucy McGee will present the preliminary results of her project that involves tracing magmatic degassing timescales at Soufriere Hills Volcano using short-lived Uranium series isotopes.

The Soufrière Hills Volcano, on the Caribbean island of Montserrat, one of the most intensively studied and constantly monitored volcanic systems in the world. Since 1995, the island has seen five phases of eruption, and the last eruptive phase ended in 2010. Mafic recharge is thought to contribute volatiles which may lead to system overpressure and trigger a volcanic eruption. Enclaves of mafic material are a notable feature within the andesitic dome collapse material from all five eruptive phases.

210Pb-226Ra disequilibria – part of the decay chain of Uranium – is a powerful tool in tracing gas movement within recently erupted (<100 years) volcanic material, as one of the intermediary daughters involved in the chain (222Rn) is released in the gas phase of magmas. Subsequent deficits or excesses of 210Pb over 226Ra provide information on the timescales of gas transfer and two possible scenarios: the magma is recharging (recent gas fluxing and 210Pb excesses in the host andesite), or the system is waning (210Pb deficits).