Final published version
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Thermal impact of dykes on ignimbrite and implications for fluid flow compartmentalisation in calderas
AU - Kennedy, Ben M.
AU - Heap, Michael J.
AU - Burchardt, Steffi
AU - Villeneuve, Marlène
AU - Tuffen, Hugh
AU - Gilg, H. Albert
AU - Davidson, Jonathan
AU - Duncan, Neryda
AU - Saubin, Elodie
AU - Gestsson, Einar Bessi
AU - Anjomrouz, Marzieh
AU - Butler, Philip
PY - 2022/2/4
Y1 - 2022/2/4
N2 - 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.
AB - 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.
KW - Earth and Planetary Sciences (miscellaneous)
KW - Geochemistry and Petrology
KW - Geology
KW - Geophysics
U2 - 10.30909/vol.05.01.5573
DO - 10.30909/vol.05.01.5573
M3 - Journal article
VL - 5
SP - 75
EP - 93
JO - Volcanica
JF - Volcanica
SN - 2610-3540
IS - 1
ER -