Dr Madeleine Humphreys


Royal Society Research Fellow

Email: madeleine.humphreys@earth.ox.ac.uk
TEL: +44 (1865) 272020
FAX: +44 (1865) 272072

Research Profile

I am a Royal Society University Research Fellow and part of the Igneous Petrology/ Volcanology group at Oxford, and the Layered Intrusions Research Group. My research interests are in understanding how magma evolves and moves within and beneath volcanoes, and how this can influence volcanic activity. I use the texture and chemistry of rocks and their constituent minerals to understand their magmatic history.

I was recently awarded the Max Hey Medal for 2012 by the Mineralogical Society.

Current research students

Iona McIntosh 2010- (Durham; co-supervised by Ed Llewellin) - Development of volatile gradients around bubbles 

Arc magmatism

Subduction zone volcanoes pose a major hazard across the globe. My work aims to answer fundamental questions relating to shallow crystallisation, storage, mixing and degassing of magma. I use petrological observation, precise measurements of volatiles and trace elements in melt inclusions, and mineral chemistry to place constraints on these processes.

Crystal mush solidification

The strength and behaviour of solidifying magma is controlled by the way it crystallises. I use immobile trace element concentrations in cumulus minerals and overgrowths, to constrain how porosity is gradually occluded during late-stage crystallisation of magma. This affects whether and how residual melt can migrate along grain boundaries and through small pores, with implications for the formation of ore deposits.   

 

Selected Publications

In press or accepted:

Phillips, J.C., Humphreys, M.C.S., Daniels, K., Brown, R. & Witham, F. (2012). Columnar joints produced by cooling in basalt. Bulletin of Volcanology (in review). 

Holness, M.B., Humphreys, M.C.S., Sides, R., Helz, R. & Tegner, C. (2012). Towards an understanding of low dihedral angles in mafic rocks. Journal of Geophysical Research (in press). 

2011 

Holness, M.B., Stripp, G.R., Humphreys, M.C.S., Veksler, I. & Nielsen, T.F.D. (2011). Silicate liquid immiscibility within the crystal mush: Late-stage magmatic microstructures in the Skaergaard Intrusion, East Greenland. Journal of Petrology 52, 175-222

Humphreys, M.C.S. (2011). Silicate liquid immiscibility within the crystal mush: Evidence from Ti in plagioclase from the Skaergaard Intrusion. Journal of Petrology 52, 147-174

2010 

Humphreys, M.C.S. & Holness, M.B. (2010). Melt-rich segregations in the Skaergaard Marginal Border Series: Tearing of a vertical silicate mush. Lithos 119, 181-192

Edmonds, M., Aiuppa, A., Humphreys, M., Moretti, R., Guidice, G., Martin, R.S., Herd, R.A. & Christopher, T. (2010). Excess volatiles supplied by mingling of mafic magma at an andesite arc volcano. G-cubed 11, Q04005 

Humphreys, M.C.S., Edmonds, M., Christopher, T. & Hards, V. (2010). Magma hybridisation and diffusive exchange recorded in heterogeneous glasses from Soufrière Hills Volcano, Montserrat. Geophysical Research Letters 37, L00E06

Christopher, T., Edmonds, M., Humphreys, M.C.S. & Herd, R.A. (2010). Volcanic gas emissions from Soufrière Hills Volcano, Montserrat 1995-2009, with implications for mafic magma supply and degassing. Geophysical Research Letters 37, L00E04

2009 

Humphreys, M.C.S., Edmonds, M, Christopher, T. & Hards, V. (2009). Chlorine variations in the magma of Soufrière Hills Volcano, Montserrat: Insights from Cl in amphibole. Geochimica et Cosmochimica Acta 73, 5693-5708

Humphreys, M.C.S. (2009). Chemical evolution of intercumulus liquid, as recorded in plagioclase overgrowth rims from the Skaergaard Intrusion. Journal of Petrology 50, 127-145

Humphreys, M.C.S., Christopher, T. & Hards, V. (2009). Microlite transfer by disaggregation of mafic inclusions following magma mixing at Soufrière Hills Volcano, Montserrat. Contributions to Mineralogy and Petrology 157, 609-624

2008 

Sparks, R.S.J., Folkes, C.B., Humphreys, M.C.S., Barford, D., Clavero, J., Mayel, S., McNutt, S. & Pritchard, M. (2008). Uturuncu volcano, Bolivia: Volcanic unrest due to mid-crustal magma intrusion. American Journal of Science, 308, 727-769

Humphreys, M.C.S., Menand, T., Blundy, J.D., Klimm, K. (2008) Magma ascent rates in explosive eruptions: Constraints from H2O diffusion in melt inclusions.  Earth and Planetary Science Letters, 270, 25-40

Humphreys, M.C.S., Blundy, J.D. & Sparks, R.S.J. (2008). Shallow-level decompression crystallisation and deep magma supply at Shiveluch Volcano. Contributions to Mineralogy and Petrology,155, 45-61

2006 

Blundy, J., Cashman, K. & Humphreys, M. (2006). Magma heating by decompression-driven crystallisation beneath andesite volcanoes. Nature, 443, 76-80

Humphreys, M.C.S., Blundy, J.D. & Sparks, R.S.J. (2006). Magma evolution and open system processes at Shiveluch Volcano: Insights from phenocryst zoning. Journal of Petrology, 47, 2303-2334.

Dirksen, O., Humphreys, M.C.S., Pletchov, P., Melnik, O., Demyanchuk, Y., Sparks, R.S.J. & Mahony, S. (2006). The 2001-2004 dome-forming eruption of Shiveluch Volcano, Kamchatka: Observation, petrological investigation and numerical modelling. Journal of Volcanology and Geothermal Research, 155, 201-226.

Humphreys, M.C.S., Kearns, S., Blundy, J.D. (2006). SIMS investigation of electron-beam damage to hydrous glasses. American Mineralogist, 91, 667-679

2003 

Holness, M.B. and Humphreys, M.C.S. (2003). The Traigh Bhàn na Sgùrra sill, Isle of Mull: Flow localisation in a major magma conduit. Journal of Petrology, 44, 1961-1976