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Gas-driven filter pressing in magmas: Insights into in-situ melt segregation from crystal mushes

Pistone, M.; Arzilli, F.; Dobson, K.J.; Cordonnier, B.; Reusser, E.; Ulmer, P.; Marone, F.; Whittington, A.G.; Mancini, L.; Fife, J.L.; Blundy, J.D.

Gas-driven filter pressing in magmas: Insights into in-situ melt segregation from crystal mushes Thumbnail


Authors

M. Pistone

F. Arzilli

K.J. Dobson

B. Cordonnier

E. Reusser

P. Ulmer

F. Marone

A.G. Whittington

L. Mancini

J.L. Fife

J.D. Blundy



Abstract

Gas-driven filter pressing is the process of melt expulsion from a volatile-saturated crystal mush, induced by the buildup and subsequent release of gas pressure. Filter pressing is inferred to play a major role in magma fractionation at shallow depths (<10 km) by moving melt and gas relative to the solid, crystalline framework. However, the magmatic conditions at which this process operates remain poorly constrained. We present novel experimental data that illustrate how the crystal content of the mush affects the ability of gas-driven filter pressing to segregate melt. Hydrous haplogranite (2.1 wt% water in the melt) and dacite (4.2 wt% water in the melt) crystal mushes, with a wide range of crystallinities (34–80 vol% crystals), were investigated using in-situ, high-temperature (500–800 °C) synchrotron X-ray tomographic microscopy with high spatial (3 μm/pixel) and temporal resolution (∼8 s per three-dimensional data set). Our experimental results show that gas-driven filter pressing operates only below the maximum packing of bubbles and crystals (∼74 vol%). Above this threshold, the mush tends to fracture and gas escapes via fractures. Therefore, the efficiency of gas-driven filter pressing is promoted close to the percolation threshold and in situations where a mush inflates slowly relative to build-up of pressure and expulsion of melt. Such observations offer a likely explanation for the production of eruptible, crystal-poor magmas within Earth’s crust.

Citation

Pistone, M., Arzilli, F., Dobson, K., Cordonnier, B., Reusser, E., Ulmer, P., …Blundy, J. (2015). Gas-driven filter pressing in magmas: Insights into in-situ melt segregation from crystal mushes. Geology, 43(8), 699-702. https://doi.org/10.1130/g36766.1

Journal Article Type Article
Acceptance Date Jun 1, 2015
Online Publication Date Jul 1, 2015
Publication Date Aug 1, 2015
Deposit Date May 5, 2016
Publicly Available Date Mar 28, 2024
Journal Geology
Print ISSN 0091-7613
Electronic ISSN 1943-2682
Publisher Geological Society of America
Peer Reviewed Peer Reviewed
Volume 43
Issue 8
Pages 699-702
DOI https://doi.org/10.1130/g36766.1

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