Geochemical and lithostratigraphic constraints on the formation of pillow-dominated tindars from Undirhlíðar quarry, Reykjanes Peninsula, southwest Iceland

Pollock, Meagen; Edwards, Benjamin R.; Hauksdóttir, Steinunn; Alcorn, Rebecca; Bowman, L.

doi:10.1016/j.lithos.2014.04.023

Cited by 18 publications

(30 citation statements)

References 67 publications

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“…These tindars are distinguished from tuff cones as they do not present quaquaversal (circular radially outward dipping) structures and instead are linear features with beds dipping away from the ridge axis. The linear ridge of fragmental deposits with an intrusive core is typical of tindars described from numerous locations in Iceland and British Columbia (Werner and Schmincke 1999;Schopka et al 2006;Edwards et al 2009;Jakobsson and Gudmundsson 2008;Mercurio 2011;Pollock et al 2014).…”

Section: Tindarsmentioning

confidence: 92%

“…Tindars have also been described composed predominantly of pillow lavas, but presenting a linear morphology (Werner and Schmincke 1999;Höskuldsson et al 2006;Edwards et al 2009;Pollock et al 2014). Austurfjöll tindars are composed predominantly of ash and lapilli tuffs (Lt1, At1, Lt2, At2) and are, in most cases, cored with a feeder dike that may have a tabular and/or pillowed morphology (Figure 7a).…”

Section: Tindarsmentioning

confidence: 99%

“…Tindars are linear features constructed from vents aligned along an eruptive fissure, and each tindar is considered to be the product of one eruptive episode, like at Helgafell (Schopka et al 2006), Sveifluhals (Mercurio 2011), and Undirhlíðar (Pollock et al 2014) in Iceland. The tindars at Austurfjöll are broadly similar to tindars described elsewhere (Mercurio 2011), with an important difference at Austurfjöll being the close proximity, and overlapping, of a large number of tindars.…”

Section: Multi-vent Fissure-fed Glaciovolcanic Massifmentioning

confidence: 99%

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Ice-confined construction of a large basaltic volcano—Austurfjöll massif, Askja, Iceland

et al. 2019

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Austurfjöll is the largest basaltic glaciovolcanic massif at Askja volcano (Central Iceland), and through detailed studies of its volcanological and geochemical characteristics, we provide a detailed account of the sequence and structure of the ice-confined construction of a large Icelandic basaltic volcano. In particular, Austurfjöll represents a geometry of vents, and resulting glaciovolcanic morphology, not previously documented in ice-confined basaltic volcanoes. Austurfjöll was constructed during two major phases of basaltic volcanism; via seven eruptive episodes through disperse fissure-dominated eruptions. The earliest episode involved a rare and poorly-exposed example of subaerial activity, and this was succeeded by six episodes involving the eruption of ice-confined pillow lavas and numerous overlapping fissure eruptions of phreatomagmatic tephra. Evidence of local subaerial lavas and tephras indicates the local growth of eruptive centers above englacial lake levels, and subsequent flooding, but no prolonged subaerial activity. Localized ice-contact facies, paleowater levels and diamictons indicate the position and thickness of the ice was variable during the construction of Austurfjöll, and eruptive activity likely occurred in multiple and variable level melt-water lakes during the last glacial period. Lithofacies evidence including gradational transitions from effusive to explosive deposits, superposition of fragmental facies above coherent facies, and drainage channels suggest that changes in eruptive style were driven largely by external factors such as drainage and the increasing elevation of the massif. This study emphasizes the unique character of Austurfjöll, being composed of large pillow lava sheets, numerous (>40) overlapping glaciovolcanic tindars and only localized emergent deposits, as a product of its prolonged iceconfined eruptive history, contrasts with previous descriptions of tuyas and tindars.

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Section: Tindarsmentioning

confidence: 92%

Section: Tindarsmentioning

confidence: 99%

Section: Multi-vent Fissure-fed Glaciovolcanic Massifmentioning

confidence: 99%

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Ice-confined construction of a large basaltic volcano—Austurfjöll massif, Askja, Iceland

et al. 2019

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“…Here it is used as prescribed by Rittman (1958), for deposits that are thought to result from predominantly passive (quench and mechanical) magma fragmentation, with only relatively limited explosive lava-water interaction (e.g., Skilling, 2009;Watton et al, 2013), but also including those locally remobilised (Watton et al, 2013). However, some studies have argued or assumed that (phreato)magmatic fragmentation is the dominant process forming such rocks (e.g., Tuffen, 2007;Edwards and Russell, 2011;Pollock et al, 2014).…”

Section: Lithofacies Classificationmentioning

confidence: 99%

Glaciovolcanism at Volcán Sollipulli, southern Chile: Lithofacies analysis and interpretation

Lachowycz

Pyle

Gilbert

et al. 2015

Journal of Volcanology and Geothermal Research

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Magma-ice-meltwater interactions produce diverse landforms and lithofacies, reflecting the multitude of factors that influence glaciovolcanism, including both magmatic (e.g., composition, eruption rate) and glacial (e.g., ice thickness, thermal regime) conditions. This is exemplified by the walls of the partly ice-filled summit caldera of Volcán Sollipulli, a stratovolcano in southern Chile, which include lithofacies from eruptions of a wide range of magma compositions beneath or in contact with ice. Here we analyse these lithofacies and hence propose new interpretations of the eruptive and glacial history of Sollipulli. The facies include a thick, laterally extensive sequence of fragmental glaciovolcanic deposits, comprising massive, mafic lava pillow-bearing hyaloclastite overlain by sills and then hyaloclastic debris flow deposits (similar to Dalsheidi-type sequences). The distribution and thickness of these units indicate an unusual abundance of magma-meltwater interaction for an arc stratovolcano in temperate latitudes, perhaps due to eruptions beneath a thick ice cap. Coherent lava coulées, domes, lobes, and stacks of basaltic andesite-trachydacite composition are present around the top of the caldera rim; these display morphologies and fracture patterns on caldera-facing margins that indicate that the caldera was filled with ice when these lavas were erupted. The lithofacies characterised in this study demonstrate the diversity of glaciovolcanism that is possible at arc stratovolcanoes capped by temperate ice or with ice-filled calderas, and the potential for uncertainties in inference of the palaeoenvironmental conditions of their emplacement.

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“…We examined major element composition using an XRF (Rigaku ZSX Primus II) at the College of Wooster following methods of Pollock et al (2014). The resulting major element concentrations were used to characterize rock type by total alkali versus silica (TAS, Le Bas et al 1985) and Jensen Cation (Le Maitre et al 1989) plots, since samples could have undergone metasomatic loss of alkalis during greenschist facies alteration (Rollinson 1993).…”

Section: Bulk Rock Geochemistrymentioning

confidence: 99%

Geochemical Investigation of Anomalous Arsenic Enrichment in the Santiago Peak Volcanics of Southern California

Johnston¹

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I would like to first acknowledge the sources of funding that made this project possible: 1) the San Diego Association of Environmental Professionals Student Scholarship, and 2) the Stephen E. Sullivan Memorial Scholarship. I could not have conducted this study without the generous support of these scholarships, as they were primarily used to cover research costs. I would also like to thank those who kindly allowed me to use their scientific instruments and provided training: Dr.

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Geochemical and lithostratigraphic constraints on the formation of pillow-dominated tindars from Undirhlíðar quarry, Reykjanes Peninsula, southwest Iceland

Cited by 18 publications

References 67 publications

Ice-confined construction of a large basaltic volcano—Austurfjöll massif, Askja, Iceland

Ice-confined construction of a large basaltic volcano—Austurfjöll massif, Askja, Iceland

Glaciovolcanism at Volcán Sollipulli, southern Chile: Lithofacies analysis and interpretation

Geochemical Investigation of Anomalous Arsenic Enrichment in the Santiago Peak Volcanics of Southern California

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