Origin of a rhyolite that intruded a geothermal well while drilling at the Krafla volcano, Iceland

Geology
By: , and 

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Abstract

Magma flowed into an exploratory geothermal well at 2.1 km depth being drilled in the Krafla central volcano in Iceland, creating a unique opportunity to study rhyolite magma in situ in a basaltic environment. The quenched magma is a partly vesicular, sparsely phyric, glass containing ∼1.8% of dissolved volatiles. Based on calculated H2O-CO2 saturation pressures, it degassed at a pressure intermediate between hydrostatic and lithostatic, and geothermometry indicates that the crystals in the melt formed at ∼900 °C. The glass shows no signs of hydrothermal alteration, but its hydrogen and oxygen isotopic ratios are much lower than those of typical mantle-derived magmas, indicating that this rhyolite originated by anhydrous mantle-derived magma assimilating partially melted hydrothermally altered basalts.

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Publication type Article
Publication Subtype Journal Article
Title Origin of a rhyolite that intruded a geothermal well while drilling at the Krafla volcano, Iceland
Series title Geology
DOI 10.1130/G31393.1
Volume 39
Issue 3
Year Published 2011
Language English
Publisher Geological Society of America
Contributing office(s) Volcano Science Center
Description 4 p.
First page 231
Last page 234
Country Iceland
Other Geospatial Krafla volcano
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