Vikrahraun—the 1961 basaltic lava flow eruption at Askja, Iceland: morphology, geochemistry, and planetary analogs

Ukstins, I. A.; Graettinger, A. H.; Blasizzo, A. Y.; Carley, Tamara L.; Peate, D. W.; Scheidt, S. P.; Moritz, A. J.; Thines, J. E.

Vikrahraun—the 1961 basaltic lava flow eruption at Askja, Iceland: morphology, geochemistry, and planetary analogs

Abstract

We examine the morphology and chemistry of the Vikrahraun basaltic eruption emplaced at Askja Volcano, Iceland, from Oct. 26–Dec. 17, 1961. The eruption had three eruptive events, initiating with aʻa and followed by alternating aʻa and pahoehoe lava flow emplacement. We determine that while the eruption is chemically homogenous (Fe/Mg=1.9–2.2, 47–52 wt.% SiO2), it demonstrates transitions from high to low viscosity lava flow morphologies. Aʻa flows have a total crystallinity (phenocryst and microlite abundance by area) ranging from 85–100%, which increases by 1% per km from the vents, while pahoehoe flows range from 55–86% and increase at a higher rate of 5% per km. Vesicularity systematically decreases with distance from the vent by 3% per km. Pahoehoe and vent samples have calculated temperatures 50 °C higher than aʻa samples, which we interpret to be due to the difference between tube fed pahoehoe and open channel aʻa lavas. The homogenous nature of the Vikrahraun lava makes it an excellent testbed to study the effects of observational scale and satellite resolution on the interpretation of surficial textures. Festoons, which are downslope pointed convex ridges from 1 to 5 m high and ~10 m long, are observed in event 2 aʻa lavas in satellite imagery and topographic profiles. Features of this scale have previously only been documented in terrestrial rhyolitic lavas, leading planetary researchers to infer that festooned lava flows on Venus and Mars may be silicic. The diverse morphologies and homogenous composition make Vikrahraun an important planetary analog, where morphological complexity is over-attributed to chemical variation and suggests the need to re-evaluation planetary lava flow interpretations.

Title	Vikrahraun—the 1961 basaltic lava flow eruption at Askja, Iceland: morphology, geochemistry, and planetary analogs
Creator	Ukstins, I. A.
	Graettinger, A. H.
	Blasizzo, A. Y.
	Carley, Tamara L.
	Peate, D. W.
	Scheidt, S. P.
	Moritz, A. J.
	Thines, J. E.
Publisher	Earth, Planets and Space
Academic Department	Geology & Environmental Geosciences
Division	Natural Sciences
Organization	Lafayette College
Date Issued	2022
Date Available	2022-11-15
Type	Article
Language	English
Keyword	Basalt textures
	Remote sensing
	morphology
	Geochemistry
	Askja, Iceland
	Planetary analogs
Bibliographic Citation	Basizzo, A. Y., et al. 2022 “Vikrahraun—the 1961 basaltic lava flow eruption at Askja, Iceland: morphology, geochemistry, and planetary analogs.” Earth, Planets and Space 74: 168.
Standard Identifier	DOI 10.1186/s40623-022-01711-5
Standard Identifier	Handle 10385/xk81jm84k
Permalink	http://hdl.handle.net/10385/xk81jm84k
Rights Statement	Creative Commons - Attribution
Rights Holders	Peate, D. W.
	Thines, J. E.
	Scheidt, S. P.
	Carley, Tamara L.
	Graettinger, A. H.
	Moritz, A. J.
	Ukstins, I. A.
	Blasizzo, A. Y.