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

N1 - Funding Information: BK acknowledges NZ MBIE catalyst grant energy straight from magma. Permission to export samples from Iceland was granted by the Icelandic Institute of Natural History. We thank Rob Spiers, Shaun Mucalo, and Bertrand Renaudi? for preparing the laboratory samples. MJH acknowledges support from the Institut Universitaire de France (IUF). MJH and HT are indebted to the Royal Society International Exchanges program. HT was supported by Royal Society University Research Fellowship UF140716. EBG and SB acknowledge support by Landsvirkjun through a student research grant awarded to EBG. ND, MA, and PB acknowledge the support of the entire MARS collaboration. We thank Richard Brown and Stephan Pansino for constructive reviews. Funding Information: BK acknowledges NZ MBIE catalyst grant energy straight from magma. Permission to export samples from Iceland was granted by the Icelandic Institute of Natural History. We thank Rob Spiers, Shaun Mucalo, and Bertrand Renaudié for preparing the laboratory samples. MJH acknowledges support from the Insti-tut Universitaire de France (IUF). MJH and HT are indebted to the Royal Society International Exchanges program. HT was supported by Royal Society University Research Fellowship UF140716. EBG and SB acknowledge support by Landsvirkjun through a student research grant awarded to EBG. ND, MA, and PB acknowledge the support of the entire MARS collaboration. We thank Richard Brown and Stephan Pansino for constructive reviews. Publisher Copyright: © 2022 The Author(s). Publisher Copyright: © 2022 The Author(s).

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 - Alteration

KW - Caldera

KW - Hydrothermal

KW - Permeability

KW - Volcano

UR - http://www.scopus.com/inward/record.url?scp=85125183599&partnerID=8YFLogxK

U2 - 10.30909/VOL.05.01.7593

DO - 10.30909/VOL.05.01.7593

M3 - Article

AN - SCOPUS:85125183599

VL - 5.2022

SP - 75

EP - 93

JO - Volcanica

JF - Volcanica

SN - 2610-3540

IS - 1

ER -