Thermal impact of dykes on ignimbrite and implications for fluid flow channelisation in a caldera

Main Article Content

Ben Kennedy
https://orcid.org/0000-0001-7235-6493
Michael Heap
https://orcid.org/0000-0002-4748-735X
Steffi Burchardt
https://orcid.org/0000-0002-3316-658X
Marlène Villeneuve
https://orcid.org/0000-0001-6001-0786
Hugh Tuffen
https://orcid.org/0000-0001-8829-1751
H. Albert Gilg
https://orcid.org/0000-0003-4304-9763
Jonathan Davidson
https://orcid.org/0000-0002-7700-9359
Neryda Duncan
https://orcid.org/0000-0002-9221-6655
Elodie Saubin
https://orcid.org/0000-0003-4379-5600
Einar Bessi Gestsson
https://orcid.org/0000-0003-4375-1114
Marzieh Anjomrouz
https://orcid.org/0000-0001-6454-6422
Philip Butler
https://orcid.org/0000-0001-9878-2140

Abstract

Ignimbrites within calderas host intrusions with hazardous and/or economically significant hydrothermal systems. The Hvítserkur ignimbrite at Breiðuvík caldera, north-eastern Iceland, is intruded by basaltic dykes. Our data show that the ignimbrite immediately adjacent to the dyke is hard, dark-coloured, recrystallised quartz, plagioclase, and alkali feldspar with a low permeability and porosity and frequent macrofractures. At 1-2 m from the dyke, the ignimbrite is hard, dominantly glassy with pervasive perlitic microfractures, has high permeability, but low porosity and frequent macrofractures. A narrow zone of pervasive unlithified clay exists 2 m from the dyke. Beyond this, the ignimbrite is soft and zeolite-rich, has low permeability, high porosity and fewer macrofractures. The dyke intrusion promoted a narrow zone of welding, fracturing and perlitisation in the ignimbrite resulting in high permeability and focussed alteration. Our study shows how intrusions and their thermal aureoles create vertical pathways for, and horizontal barriers to, geothermal fluid flow.

Downloads

Download data is not yet available.

Article Details

How to Cite
Kennedy, B., Heap, M., Burchardt, S., Villeneuve, M., Tuffen, H., Gilg, H. A., Davidson, J., Duncan, N., Saubin, E., Gestsson, . E. B., Anjomrouz, M. and Butler, P. (2022) “Thermal impact of dykes on ignimbrite and implications for fluid flow channelisation in a caldera”, Volcanica, 5(1), pp. 75–93. doi: 10.30909/vol.05.01.7593.
Section
Articles

Most read articles by the same author(s)