Journal article
Timescales of degassing and conduit dynamics inferred from ²¹⁰Pb–²²⁶Ra disequilibria in Volcán de Colima 1998–2010 andesitic magmas
Geological Society special publication, Vol.422(1), pp.189-206
2015
DOI: 10.1144/SP422.5
Abstract
: Determining the timescales of magma degassing is essential for understanding the
mechanisms controlling the eruption style and the dynamics of magmatic systems. Towards this
end, we measured 210Pb–226Ra disequilibria in andesite lavas erupted from Volca´n de Colima
between 1998 and 2010. (210Pb/226Ra)0 activity ratios range from 0.86 to 1.09, and are best
explained in terms of 222Rn degassing and accumulation. The range in 210Pb deficits indicates
that the timescales of 222Rn degassing did not exceed 11 years. 210Pb excesses are rare and
small (,10%), which signifies that 222Rn degassing is more effective than 210Pb accumulation
in this intermediate system despite the relatively low gas output at the surface. The absence of significant 210Pb excesses strongly suggests that the volcanic activity results from episodic ascent of
small magma batches through the vapour-saturated section of the magmatic system. Overall, the
degassing models based on 210Pb–226Ra disequilibrium suggest an open and complex subvolcanic
magmatic system comprising several conduits in which multiple magma batches reside for up to
10 years. Shifts from effusive to explosive Vulcanian eruptive phases are not related to changes
in degassing mode on timescales resolvable using 210Pb–226Ra disequilibria.
Details
- Title: Subtitle
- Timescales of degassing and conduit dynamics inferred from ²¹⁰Pb–²²⁶Ra disequilibria in Volcán de Colima 1998–2010 andesitic magmas
- Creators
- Olivier ReubiKenneth W. W SimsNicholas VarleyMark ReaganJost Eikenberg
- Resource Type
- Journal article
- Publication Details
- Geological Society special publication, Vol.422(1), pp.189-206
- DOI
- 10.1144/SP422.5
- ISSN
- 0305-8719
- eISSN
- 2041-4927
- Language
- English
- Date published
- 2015
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9983984521602771
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