The Open UniversitySkip to content
 

Time scales of crystal residence and magma chamber volume from modelling of diffusion profiles in phenocrysts: Vesuvius 1944

Morgan, D.J.; Blake, S.; Rogers, N.W.; De Vivo, B.; Rolandi, G.; Macdonald, R. and Hawkesworth, C.J. (2004). Time scales of crystal residence and magma chamber volume from modelling of diffusion profiles in phenocrysts: Vesuvius 1944. Earth and Planetary Science Letters, 222(3-4) pp. 933–946.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/j.epsl.2004.03.030
Google Scholar: Look up in Google Scholar

Abstract

Diffusional smoothing of Fe–Mg compositional gradients in clinopyroxene crystals from the 1944 eruption of Vesuvius is used to determine the preeruption residence times of crystals at magmatic temperatures. The result is a distribution of crystal residence times from one sample that can be used to constrain magma chamber volumes. Diffusional zones between compositionally distinct cores and rims were observed by backscattered electron (BSE) imaging to vary in width from 1.6 to 11.9 μm and represent storage of crystals at magmatic temperatures for periods ranging from 4.5 months up to 9 years prior to eruption. The distribution of residence times is skewed to young ages and is best explained by the open-system behaviour of an 8.0×107 m3 chamber that received an input of between 3.5×107 and 7.0×107 m3 in the final 6 months prior to eruption. The calculated inputs, compared with contemporary observations of the emitted magma volumes, implies that some 3.0×107–6.5×107 m3 of magma input did not erupt but was accommodated by chamber expansion before the 1944 eruption. This would place the preeruptive chamber volume between 1.15×108 and 1.5×108 m3. The eruption was then triggered by a further input of 1.9×107 m3 which forced the extrusion of a similar volume of relatively degassed magma as lava flows prior to the fire-fountaining episode. The backscattered electron imaging technique for residence time determination has great potential in unravelling the histories of populations of phenocrysts in many volcanic systems.

Item Type: Journal Article
ISSN: 1385-013X
Extra Information: Some of the symbols may not have transferred correctly into this bibliographic record and/or abstract.
Keywords: residence times; diffusion; clinopyroxene; Vesuvius
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 3898
Depositing User: Nick Rogers
Date Deposited: 04 Jul 2006
Last Modified: 02 Dec 2010 19:50
URI: http://oro.open.ac.uk/id/eprint/3898
Share this page:

Altmetrics

Scopus Citations

Actions (login may be required)

View Item
Report issue / request change

Policies | Disclaimer

© The Open University   + 44 (0)870 333 4340   general-enquiries@open.ac.uk