Project highlights

  • A unique petrological perspective gained from looking inside an active volcano
  • Contribute to understanding one of the principal controls on volcanic eruptions and volcanic hazard assessment
  • Develop expertise in a variety of field and laboratory techniques to resolve the evolution of volatile elements in volcanic systems

Overview

Accurate and reliable forecasting of volcanic eruptions remains one of the principal objectives of modern volcanology and is often reliant on real-time gas monitoring. Accurate interpretation of gas monitoring data relies on a quantification of the likely dissolved volatile (H2O, CO2, S, F, Cl) contents in the pre-eruptive magma. This is particularly the case when monitoring persistently degassing volcanoes that have not undergone a major eruption within the lifetime of the gas monitoring system. At present, melt inclusion studies represent the state of the art in reconstructing pre-eruptive magmatic volatile contents. However, melt inclusions are affected by a number of post-entrapment processes that can modify or reset their volatile contents on timescales of hours to years (e.g. Hartley et al., 2014).

Recent studies have highlighted the potential of the mineral apatite as an alternative proxy for magmatic volatile contents (e.g. Stock et al., 2016). The apatite crystal structure can host a range of volatile species that are important for understanding volatile budgets (e.g. F, Cl, OH, C, Br and S). Apatite is more retentive of these elements than silicate melts or glasses, and it can preserve a record of magmatic volatile contents even in volcanic rocks where the glass is largely degassed. Apatite also hosts other trace and redox-sensitive elements that can be used to build a detailed picture of pre-eruptive magma storage conditions (Miles et al., 2013).

This project aims to explore the extent to which apatite and melt inclusions preserve similar information about volatile evolution in magmatic systems. By integrating the apatite and melt inclusion records, we aim to develop forensic petrological tools to reconstruct pre-eruptive magma storage conditions and degassing budgets that will inform the interpretation of gas monitoring data at actively degassing volcanoes.

The project will initially focus on Soufrière Hills Volcano, Montserrat (e.g. Edmonds et al., 2003) where major eruptions occurred between 1995 and 2010. The gas chemistry was monitored by fourier-transform infra-red (FTIR) spectroscopy during several of these eruptions, meaning that measured gas compositions can be related directly to volcanic products erupted on known dates.

Host

University of Leicester

Theme

  • Dynamic Earth

Supervisors

Project investigator

  •  Dr Andrew Miles

 

Co-investigators

  • Dr Margaret Hartley (University of Manchester)
  • Dr Tiffany Barry (University of Leicester)

How to apply

Methodology

Samples will either be obtained from existing collections or ideally gathered directly from the Soufrière Hills volcano for geochemical analysis. Quantitative petrological and compositional characterisation will be carried out at the University of Leicester using a scanning electron microscope (SEM) and x-ray fluorescence (XRF) analysis. Apatite will be analysed in situ from thin section, with major element compositions determined by electron microprobe at the University of Manchester. Volatile elements will be measured by secondary ionisation mass spectrometry (SIMS) at the University of Edinburgh following a grant application to the facility. Major elements, F, S, and Cl of melt inclusions within silicate minerals and host minerals will be determined by electron microprobe analysis, while other volatiles and trace/rare earth elements will be analysed by SIMS.

Training and skills

You will become proficient in the use of analytical equipment including quantitative evaluation of minerals, SEM and XRF, and high-resolution mass spectrometry. This combination of state-of-the-art analytical methods will provide you with a unique set of skills that will be attractive to industrial and academic employers. You will join a thriving community of igneous and applied researchers, and work closely with members of two major NERC-funded projects (FAMOS – From Arc Magmas to Ore Systems, and TeaSe – Te and Se Cycling and Supply), as well as chemists and material scientists within the Centre for Sustainable Resource Extraction.

Partners and collaboration

The student will benefit from supervision at two leading institutions (the Universities of Leicester and Manchester). They will also attend the NERC-funded ion microprobe facility at the University of Edinburgh where they will receive full training on the UK’s only SIMS facility available for academic study.

Further details

Please contact Andrew Miles (ajm131@le.ac.uk) for further information or to discuss the project in more detail.

https://le.ac.uk/study/research-degrees/funded-opportunities/centa-phd-studentships

Possible timeline

Year 1

A thorough review of the latest literature will be conducted. Fieldwork and sample collection will be conducted on Montserrat. Training in mineral separation and SEM imaging will be provided at the University of Leicester. An application to the NERC ion microprobe facility will be made for volatile and trace element analysis of apatites and melt inclusions. Attend a national conference.

Year 2

Ongoing sample preparation and analysis. Presentation of results at large national and international conference.

Year 3

Integration of data will provide a model for volatile evolution. Publication of papers. Presentation at large national and international conference.

Further reading

Edmonds, M., Oppenheimer, C., Pyle, D.M., Herd., R.A., Thompson, G., SO2 emissions from Soufrière Hills Volcano and their relationship to conduit permeability, hydrothermal interaction and degassing regime. Journal of Volcanology and Geothermal Research 124 (1-2), 23-43.

Hartley, M.E., Bali, E., Mclennan, J., Neave, D., Halldorsson, S.A., Melt inclusion constrains on petrogensis of the 2014-2015 Holuhraun eruption, Iceland. Contributions to Mineralogy and Petrology, 173:10.

Miles, A.J., Graham, C.M., Hawkesworth, C.J., Gillespie, M.R., Hinton, R.W., EIMF, 2013, Evidence for distinct stages of magma history recorded by the compositions of accessory apatite and zircon: Contributions to Mineralogy and Petrology, v. 166, p. 1-19.

Stock, M.J., Humphreys, M.C.S., Smith, V.C., Isaia, R., and Pyle, D.M., 2016, ‘Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions’. Nature Geoscience, 9, 243. 1-2

COVID-19

The essential laboratory work within this project can be carried out within University of Leicester’s and Manchester’s Covid-secure facilities. Automated and remote analytical routines mean that analytical facilities can be run even with minimal presence on campus. Gas monitoring data is available digitally. Samples will ideally be collected during a two week field season, but existing sample suites can be obtained from UK institutions.