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FAQ

What is CRITMAG?
Who is involved with the project?
What are the main research goals?
What techniques are being used in the project?
Which volcanoes are involved in the study?
Can I reuse images featured on this website?


What is CRITMAG?

CRITMAG (Critical Behaviour in Magmatic Systems) is the name of an European Research Council (ERC) Advanced Grant that was awarded to Professor Jon Blundy of the University of Bristol in 2010. The overarching aim of the project is to link experimental and observational petrology to understand magmatic behaviour beneath hazardous volcanoes.

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Who is involved in the project?

The project is led by Professor Jon Blundy in the School of Earth Sciences at the University of Bristol, UK. Other staff funded by the project include several post-doctoral research associates and PhD students, and research outputs include collaborations with workers at other universities and research institutions (Addis Ababa, Australian National University, Colima, Durham, ETH Zürich, Geneva, Imperial College London, Leeds, Oregon, Oxford, Ruhr-Universität Bochum, Savoie, USGS).

Piston cylinder experiment

Pressurisation of a high pressure piston cylinder experiment at the University of Bristol

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What are the main research goals?

Volcanic activity that occurs in, and forms, continental crust is periodic on a very wide range of timescales. Releases of magma vary from pulses of continental crustal growth, through formation of granite batholiths, to small and frequent eruptions from individual volcanic centres. The cause of this periodicity is not understood.

The ultimate objective of the CRITMAG grant is to answer five fundamental questions:

  • Why is crustal magmatism episodic?
  • How are large batholiths formed of rather similar magmas over long periods of time?
  • How do large bodies of eruptible magma develop that can lead to huge, caldera-forming eruptions?
  • What controls the chemistry of crustal magmas? Why are some compositions over-represented relative to others?
  • What is the thermal structure beneath volcanic arcs and how does it evolve with time?

The project goals aim to test a novel proposal that periodicity arises because of the highly non-linear (critical) behaviour of magma crystallinity with temperature in a series of linked crustal magma reservoirs.

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What techniques are being used in the project?

CRITMAG is addressing these long-standing geological problems through a combination of high-pressure experiments, petrological studies and numerical models.  Examples of different techniques used in published work include:

  • Diffusion chronometry to constrain the frequency of magmatic pulses in the sub-volcanic reservoirs (e.g., Saunders et al., 2014, Chemical Geology; Saunders et al., 2012, Science)
  • Characterisation of glassy melt inclusions trapped inside volcanic phenocrysts (e.g., Kilgour et al., 2013, Contributions to Mineralogy and Petrology; Reubi et al., 2013, Contributions to Mineralogy and Petrology)
  • Major element analysis of mineral phases in plutonic rocks to gain estimates of conditions prevailing in magma storage regions (e.g., Tollan et al., 2012, Contributions to Mineralogy and Petrology)
  • High-pressure experiments on Mg-rich basaltic rocks to constrain the lower crustal conditions under which the shallow magmas were generated (e.g., Stamper et al., 2014, Contributions to Mineralogy and Petrology; Melekhova et al., 2013, Nature Geoscience)
  • High-pressure experiments on evolved compositions and subduction sediments to unravel the relationship between inputs and outputs to subduction volcanoes (e.g., Martindale et al., 2013, Chemical Geology;
  • Thermomechanical numerical modelling to quantify the relative the controls on the frequency and magnitude of volcanic eruptions (e.g., Caricchi et al., 2014, Nature)
  • Combining geophysical surveys with petrographic data to interpret how magma is transported through, stored in, and erupted from, the continental crust (e.g., del Potro et al., 2013, Geophysical Research Letters; Saunders et al., 2012, Science)
Zoned orthopyroxene

False colour image of a zoned orthopyroxene crystal from a Mt St Helens lava.

Click here to find out more about the facilities used by CRITMAG-funded projects.

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Which volcanoes are involved in the study?

CRITMAG field areas are spread far and wide across the globe. Recent research and fieldwork has included currently active volcanoes in Russia (Tolbachik and Bezymianny), Italy (Etna, Stromboli) and the East African Rift valley in Ethiopia. Other areas of study are volcanic ranges in the Lesser Antilles, the Andes and North America. The remit of the CRITMAG project also encompasses plutons in the Italian Alps (Adamello) and Guernsey.

Click here for full list of volcanoes and plutons involved in CRITMAG-funded research.

Sampling St Vincent

Sampling a lava flow on Soufriere St Vincent, Lesser Antilles.

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Can I reuse images featured on this website?

Yes. Unless otherwise specified, photos to be credited to “CRITMAG ERC Advanced Grant”.
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