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Apatite as a tracer for magmatic volatiles

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Apatite: new ways to understand volcanic gas

‘Volatiles’ are dissolved gases, an important component of most magmas. When magma ascends towards the Earth’s surface beneath a volcano, the dissolved gases form bubbles, which expand and accelerate the magma upwards. This is the primary fuel for explosive volcanic eruptions. Knowing the amount of gas dissolved in magmas under the ground, and whether there are bubbles of gas present, is important because it means we have a better chance of understanding how the volcano may erupt. Apatite is a very common mineral that contains halogens, water and carbon dioxide (CO2). We are developing ways to use apatite to interpret volatile behaviour in magmas before eruption. This will help us to understand the build-up towards big volcanic eruptions.

Publications

6. Lormand, C., Humphreys, M.C.S., Colby, D., Coumans, J.P., Chelle-Michou, C. & Li, W. (2024) Volatile budgets and evolution in porphyry-related magma systems, determined using apatite. Lithos (accepted)

5. Humphreys, M.C.S., Smith, V.C., Coumans, J.P., Riker, J.M., Stock, M.J., de Hoog, J.C.M. & Brooker, R.A. (2021) Rapid pre-eruptive mush reorganisation and atmospheric volatile emissions from the 12.9 ka Laacher See eruption, determined using apatite. Earth and Planetary Science Letters 576, 117198

4. Stock, M.J., Humphreys, M.C.S., Smith, V.C., Isaia, R., Brooker, R.A. & Pyle, D.M. (2018) Tracking volatile behaviour in sub-volcanic plumbing systems using apatite and glass: Insights into pre-eruptive processes at Campi Flegrei, Italy. Journal of Petrology 59, 2463-2492 

3. Riker, J.M., Humphreys, M.C.S., Brooker, R.A., de Hoog, C.J. & EIMF. (2018) First measurements of OH-C exchange and T-dependent partitioning of OH and halogens in the system apatite – silicate melt. American Mineralogist 103, 260-270 

2. Stock, M.J., Humphreys, M.C.S., Smith, V.C., Isaia, R. & Pyle, D. (2016) Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions. Nature Geoscience 9, 249-255 

1. Stock, M.J., Humphreys, M.C.S., Smith, V.C., Johnson, R.D. & Pyle, D.M. (2015). New constraints on electron-beam induced halogen migration in apatite. American Mineralogist 100, 281-293