An experimental investigation of interaction between andesite and hyperacidic volcanic lake water

Minerals
By: , and 

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Abstract

Alteration in magmatic-hydrothermal systems leads to distinct changes in rock texture and mineralogy, and a strong redistribution of elements between fluid and rock. Here, we experimentally interacted andesite scoria with hyperacidic, high-sulfidation style fluids from Kawah Ijen volcano (Indonesia) at 25 and 100˚C, seeking to reproduce the textures observed in natural samples from this volcano, and to understand the element fluxes that accompany alteration. The susceptibility to alteration in the experiments is Cu-Fe-sulphide > calcic plagioclase > pyroxene > titano-magnetite > sodic plagioclase, with complete preservation of glass. Silicate minerals alter to opaline silica, and gypsum, barite and a Zr-phase precipitate. The selective alteration of the phenocryst minerals results in a preferential release of compatible elements, as the glass is the main incompatible element host. The experiments reproduce the alteration textures of the natural samples, including the preservation of glass, but the predicted compatible over incompatible element enrichment in the alteration element flux is not observed in the natural setting. This suggests that alteration at Kawah Ijen is dominated by lithologies that lack abundant glass, in particular lava flows where the glass has devitrified, despite these lava flows having a lower surface area compared to scoria.

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Publication type Article
Publication Subtype Journal Article
Title An experimental investigation of interaction between andesite and hyperacidic volcanic lake water
Series title Minerals
DOI 10.3390/min10020096
Volume 10
Issue 2
Year Published 2020
Language English
Publisher MDPI
Contributing office(s) Volcano Science Center
Description 96, 26 p.
Country Indonesia
Other Geospatial Kawah Ijen
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