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.
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 75-93 |
| Seitenumfang | 19 |
| Fachzeitschrift | Volcanica |
| Jahrgang | 5.2022 |
| Ausgabenummer | 1 |
| DOIs | |
| Publikationsstatus | Veröffentlicht - 4 Feb. 2022 |
Bibliographische Notiz
Publisher Copyright:© 2022 The Author(s).
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.
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 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.
Publisher Copyright:
© 2022 The Author(s).