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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities
 

Lead Supervisor: Marie Edmonds, Earth Sciences

Co-Supervisors: Jon Blundy, University of Bristol

Importance of the area of research concerned: 
Volcanic emissions provide a window into unseen, deep magmatic processes. Basaltic volcanoes outgas prodigious fluxes of volatile metals and metalloids (e.g. copper, lead, arsenic) into the atmosphere (up to 105 kg/day). Arc volcanoes, in particular, may emit large fluxes of volatile metals relative to sulphur. Metal pathways in magmas are poorly understood. Some metals are sourced from the devolatilising, subducting slab; others from the mantle wedge. In the crust, metals are partitioned into various phases: metal-rich sulphide, and a saline aqueous fluid at lower pressures. Metal fluxes from arc volcanoes vary over orders of magnitude for similar magma fluxes. Understanding how and to what extent metals become enriched in an exsolved volatile phase during magma ascent is important for developing models of ore deposit formation in arc settings as well as for volcanic pollutant dispersal and environmental impact. We hypothesise that the salinity of the exsolved volatile phase may be an important control for transporting metals.
Project summary : 
This project will seek to understand why the volcanoes of the Vanuatu arc emit large fluxes of volatile metals to the atmosphere. Analysis of erupted rocks from Yasur and Ambrym volcanoes will be carried out in order to understand the partitioning of metals between silicate melt, sulphide phases and the exsolved volatile phase. These studies will be supplemented by a field campaign to capture volcanic gas and aerosol emissions, which will be characterised for their volatile metal content and speciation. In particular the project will focus on the role of magmatic chlorine in transporting metals in the exsolved volatile phase, and will compare natural data to experiments to constrain chlorine partitioning.
What will the student do?: 
The student will undertake microanalysis of erupted, quenched rocks from Yasur and Ambrym volcanoes, Vanuatu, e.g. using scanning electron microscopy, electron probe and secondary ion mass spectrometry to quantify major, trace and volatile elements in whole rocks, glasses and sulphides. The student will undertake fieldwork in Vanuatu to acquire samples of volcanic gases and aerosols from the crater rim at Yasur and Ambrym volcanoes, and will analyse them for major anions and cations (including the volatile metals), as well as for sulphur isotopes. The student will use these observations to model metal partitioning between silicate melt, sulphide and aqueous fluid to understand the sensitivities of the magmatic system with respect to parameters such as fO2, pressure and aqueous fluid salinity and produce insights into metal processing by volcanoes and the mechanisms of metal enrichment.
References: 
Allard P, Aiuppa A, Bani P, M├ętrich N, Bertagnini A, Gauthier PJ, Shinohara H, Sawyer G, Parello F, Bagnato E, Pelletier B. Prodigious emission rates and magma degassing budget of major, trace and radioactive volatile species from Ambrym basaltic volcano, Vanuatu island Arc. Journal of volcanology and geothermal research. 2016 Aug 15;322:119-43.
Edmonds M, Mather TA, Liu EJ. A distinct metal fingerprint in arc volcanic emissions. Nature Geoscience. 2018 Oct;11(10):790.
Applying
You can find out about applying for this project on the Department of Earth Sciences page.