Supervisors: Marie Edmonds (Earth Sciences)
Importance of the area of research:
Volcanoes emit copious quantities of gases (water, sulfur, carbon) that have shaped our atmosphere over geological time. Volcanoes also emit a range of other trace species, however, which are much less understood, including metals which play important roles in both atmospheric chemistry and in catalyzing microbial activity, and provide contraints on metal partitioning between fluids and melts in arc crust where much of Earth’s ore deposits are found.
There is an abundance of data on metal emissions from volcanoes globally, yet there has been little attempt to synthesize it. Volcanoes in ocean island settings typically emit metals in abundances that mirror closely their sulfide-silicate melt partition coefficients, suggesting that they are derived from breakdown of sulfide liquids during magma ascent and degassing. In arcs, however, the distribution of metals and other trace species in volcanic gas plumes is dramatically different. The fluxes of some metal species are more than an order of magnitude greater than in ocean island settings. The controls on the flux and composition of the metals in arc gases are poorly understood but probably controlled, on an arc scale, by an interplay between sulfide saturation, vapor saturation and variability in oxidation state, set by the subducting slab.
What the student will do:
This project will both collate existing metal data from volcanoes globally and also acquire new data using sampling equipment at persistently degassing arc volcanoes. The aim of the project is to undertake a systematic review of metal outgassing and to provide, using experimental partitioning data and an understanding of sulfide systematics using chalcophile element abundances in melts, an overarching model to understand the controls on metal outputs from volcanoes in a range of tectonic settings. The student will undertake detailed fieldwork and analysis at an arc volcano, such as Masaya (Nicaragua) or Villarica (Chile), including analysis of phenocryst phases, sulfide liquids and volcanic gases using a range of techniques.
Mather TA, Witt ML, Pyle DM, Quayle BM, Aiuppa A, Bagnato E, Martin RS, Sims KW, Edmonds M, Sutton AJ, Ilyinskaya E. Halogens and trace metal emissions from the ongoing 2008 summit eruption of Kīlauea volcano, Hawaii. Geochimica et cosmochimica acta. 2012 Apr 15;83:292-323.
Edmonds, M and Mather, TA, in press, May 2017. Sulfides in volcanic systems. Elements.
Zajacz Z, Halter W. Copper transport by high temperature, sulfur-rich magmatic vapor: Evidence from silicate melt and vapor inclusions in a basaltic andesite from the Villarrica volcano (Chile). Earth and Planetary Science Letters. 2009 May 30;282(1):115-21.
Other projects involving the supervisor(s) listed can be viewed here: