Abstract
Thríhnúkagígur Volcano, Iceland, is a composite spatter cone and lava field characteristic of basaltic fissure eruptions. Lava drainback at the end of the eruption left ~60 m of evacuated conduit, and a 4 × 104 m3 cave formed by the erosion of unconsolidated tephra by the feeder dike. Field relationships within the shallow plumbing system provide three-dimensional insight into conduit formation in fissure systems. Petrographic estimates and the relative volumes of the cave and erupted lavas both indicate xenolithic tephra comprises 5–10 % of the erupted volume, which cannot be reproduced by geochemical mixing models. Although crustal xenolith entrainment is not geochemically significant, we posit that this process may be common in the Icelandic crust. The Thríhnúkagígur eruption illustrates how pervasive, poorly consolidated tephra or hyaloclastite can act as a mechanically weak pre-existing structure that provides a preferential pathway for magma ascent and may influence vent location.
| Original language | English |
|---|---|
| Pages (from-to) | 249-270 |
| Number of pages | 22 |
| Journal | Volcanica |
| Volume | 5 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 24 Aug 2022 |
Bibliographical note
Funding Information: We thank Björn Ólafsson and the rest of the staff for transporting us Inside the Volcano and for their hospitality while graciously giving us access to this exceptional field location. We acknowledge J. Normandeau for his assistance with the collection of the LiDAR data. We appreciate the thoughtful discussions with T. Furman and R. Koeberle that improved this work and the assistance of M. Saffer in collecting trace element data. This manuscript was improved by thorough and thoughtful comments by E. Gallant, an anonymous reviewer, and editor A. Graettinger. MRH was supported by a Hess Corporation Exploration & Production Technology Scholarship, the Charles E. Knopf Sr. Memorial Scholarship, and the Hi-roshi and Koya Ohmoto Graduate Fellowship in Geosciences to do this work. Additional support for was provided by NSF OISE-1324971 awarded to MDF and NSF EAR-0711456 awarded to PCL. Publisher Copyright: © The Author(s) 2022. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.Other keywords
- Conduit formation
- Crustal xenoliths
- Eruption
- Fissure
- Reykjanes peninsula
- Volcanic vent