Jerram, Dougal A. and Martin, Victoria (2008) 'Understanding crystal populations and their significance through the magma plumbing system.', in Dynamics of crustal magma transfer, storage and differentiation. London: Geological Society of London, pp. 133-148. Geological Society of London Special Publications. (304).
Crystals are rarely composed of a single crystal population that have grown solely from the batch of magma in which they are resident on emplacement, either by eruption or shallow intrusion. Close investigation of the majority of crystal populations reveal that they comprise up to four main components: phenocrysts, crystals co-genetic with their magmatic host; xenocrysts, crystals wholly, or in part, foreign to the magmatic host and magma system; antecrysts, crystals which are recycled one or several times before inclusion in the host magma but have an origin within the magmatic system; and microlites, which represent small co-genetic crystals which nucleate and grow rapidly on decompression and eruption. Textural analysis techniques are employed to quantify key aspects of the crystal population, including crystal shape, crystal size distributions, spatial distribution patterns and textural modification using dihedral angles. Santorini provides a case study of an active volcanic system where a combined textural analysis study has been developed, highlighting how the crystal population is being continuously modified by a series of replenishment and mixing events. Developing textural and microgeochemical techniques provides the next stage in the interrogation of crystal populations, linking textures to isotopic heterogeneities and providing fingerprints of where crystals are sourced and re-cycled.
|Item Type:||Book chapter|
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|Publisher Web site:||http://dx.doi.org/10.1144/SP304.7|
|Record Created:||26 May 2010 10:35|
|Last Modified:||07 Feb 2011 10:09|
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