Conference proceeding
Tracing magmatic degassing timescales at Soufriere Hills Volcano using short-lived uranium series isotopes
American Geophysical Union Fall Meeting, Vol.2016
American Geophysical Union 2016 fall meeting
12/2016
Abstract
Soufriere Hills Volcano, on the Caribbean island of Montserrat, is one of the most intensively studied and constantly monitored volcanic systems in the world. Since 1995, the island has seen five phases of eruption, interspersed with periods of quiescence of varying length. The last eruptive phase ended in 2010, and the current period of quiescence is the longest since 1995. Mafic recharge is thought to contribute volatiles which may lead to system overpressure and trigger a volcanic eruption. At Soufriere Hills Volcano, enclaves of mafic material are a notable feature within the andesitic dome collapse material from all five eruptive phases and have been the focus of several recent petrogenetic studies, meaning that they are extremely well-characterised. We present a (super 210) Pb- (super 226) Ra isotope data of enclave-andesite pairs from all five recent eruption phases of Soufriere Hills to investigate the timescale on which volatile transfer occurs prior to eruptions. (super 210) Pb- (super 226) Ra disequilibria 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 ( (super 222) Rn) is released in the gas phase of magmas. Subsequent deficits or excesses of (super 210) Pb over (super 226) Ra provide information on whether gas transfer occurred over a short time-frame or if gas fluxing from a mafic magma was maintained for some time previous to each eruption. This vital information may elucidate whether the system is recharging and preparing for a new eruptive phase or draining its current magma supply thus diminishing the possibility of further, explosive eruptions. Preliminary results suggest that gas fluxing from mafic magma was particularly effective in the first two eruptive phases, supporting the mafic-trigger hypothesis. However, we observe a possible change in this behaviour from phase 3 onwards. We complement these time-sensitive geochemical data with comparison to high resolution monitoring data with the hope that the coupling of these two techniques may aid in predicting how the system is likely to behave in the future.
Details
- Title: Subtitle
- Tracing magmatic degassing timescales at Soufriere Hills Volcano using short-lived uranium series isotopes
- Creators
- Simon Turner - Macquarie UniversityLucy Emma McGeeHeather K HandleyMark K ReaganMichael B TurnerKim BerloJenni BarclayR. Stephen J Sparks
- Resource Type
- Conference proceeding
- Publication Details
- American Geophysical Union Fall Meeting, Vol.2016
- Conference
- American Geophysical Union 2016 fall meeting
- Publisher
- American Geophysical Union
- Alternative title
- AGU 2016 fall meeting
- Language
- English
- Date published
- 12/2016
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240804102771
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