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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities

Lead Supervisor: Marie Edmonds, Earth Sciences

Co-Supervisors: David Neave, University of Manchester; Madeleine Humphreys, Durham University & Ben Ellis, ETH Zurich

Importance of the area of research concerned: 
Lithium is a critical resource for the development of Li-ion batteries, in the quest for improved methods for storing energy. An important source of lithium for mining purposes is pegmatite deposits, which are late-stage, highly evolved crystalline products of the fractionation of water-rich continental magmas. However, we still have only a limited understanding of how lithium behaves in magmas. Specifically we wish to understand how lithium concentrations in primary melts depend on mantle source, slab and crustal components; how lithium partitions into aqueous fluids during magma degassing and brine formation, and between silicate melt and crystal phases. It has been shown that continental magmas may be particularly enriched in lithium; and that lithium is often enriched in the rims of magmatic minerals (e.g. plagioclase), which has been variously linked to gas fluxing and fluid phase boiling and separation of a brine. Lithium diffuses extraordinarily fast, so these enrichments are also useful as ‘speedometers’ of volcanic processes. Vast holes in our knowledge about magmatic lithium remain, preventing a full understanding of the provenance of lithium in hydrothermal deposits.
Project summary : 
This project will undertake to reconstruct the behaviour of lithium in natural volcanic systems using observations and microanalysis. The overarching aims of the project are to (1) construct an empirical model, which may be compared to the results of partitioning experiments, to understand how, and under what conditions, lithium may become enriched in hydrothermal deposits and (2) use the trends observed in lithium abundance in natural samples to infer magmatic and volcanic processes.
What will the student do?: 
Volcanic rocks from three contrasting settings will be examined: a metaluminous arc andesite, a peralkaline rhyolite (with high halogen contents) and a continental rhyolite. Partitioning of lithium between silicate melt, crystals and an exsolved voaltile phase will be determined through analysis of elemental lithium (and other trace elements and volatiles) as well as lithium isotopes, using Secondary Ion Mass Spectroscopy at the NERC facility, supplemented by microanalysis using QEMSCAN and EPMA at the University of Cambridge. The observations will be used to understand the compatibility and volatility of lithium for different magma compositions and tectonic settings.
References - references should provide further reading about the project: 
Ellis BS, Szymanowski D, Magna T, Neukampf J, Dohmen R, Bachmann O, Ulmer P, Guillong M. Post-eruptive mobility of lithium in volcanic rocks. Nature communications. 2018 Aug 13;9(1):1-9.
Benson TR, Coble MA, Rytuba JJ, Mahood GA. Lithium enrichment in intracontinental rhyolite magmas leads to Li deposits in caldera basins. Nature communications. 2017 Aug 16;8(1):270.
You can find out about applying for this project on the Department of Earth Sciences page.
Prof Marie Edmonds
Department of Earth Sciences Graduate Administrator