Projects per year
Abstract
Ambrym, a basaltic volcano in the Vanuatu Arc, has displayed variable eruptive behaviour throughout the past century, with major eruptions occurring both on the volcano flanks and at multiple vents within its caldera. These have been interspersed with periods of relative quiescence marked by extensive passive degassing at active, intra-caldera lava lakes, which experience occasional Strombolian explosions. Volcanic rocks from all vents and eruptive styles display similar isotope and incompatible trace element compositions, suggesting that all are derived from the same primary melt by fractional crystallization. Major eruptions are commonly responsible for effusion of the least evolved lavas examined (SiO2~50 wt %; MgO~5wt %). Although all are geochemically similar, petrological differences discriminate between lavas erupted during flank and intra-caldera eruptions. Phyric basalts with homogeneous mineral compositions are common to flank eruptions, whereas crystal-rich basalts with variable mineral compositions, many not in equilibrium with their host liquid, are a feature of intra-caldera lavas. Lava lake samples are slightly more evolved than those from effusive eruptions (SiO2~51-52 wt %; MgO~4wt %), as a result of additional crystallization during periods of relative quiescence. The diverse petrology of the intra-caldera lavas can be explained by mixing of replenishment magmas similar to those erupted from the volcano flanks with residual magma from lava lake activity. Flank eruptions exploit dykes that bypass the shallow reservoir involved with lava lake activity, limiting their interaction with this component.
Original language | English |
---|---|
Pages (from-to) | 1049-1072 |
Number of pages | 24 |
Journal | Journal of Petrology |
Volume | 57 |
Issue number | 6 |
DOIs | |
Publication status | Published - 1 Jun 2016 |
Fingerprint
Dive into the research topics of 'Variable conditions of magma storage and differentiation with links to eruption style at Ambrym volcano, Vanuatu'. Together they form a unique fingerprint.Projects
- 1 Finished
-
Application of very short-lived Uranium-series isotopes to constraining Earth system processes
Turner, S., Dosseto, A. & Reagan, M.
1/01/09 → 31/12/14
Project: Research