Magma–ice–sediment interactions and the origin of lava/hyaloclastite sequences in the Síða formation, South Iceland

Banik, Tenley J.; Wallace, Paul; Höskuldsson, Ármann; Miller, Calvin F.; Bacon, Charles R.; Furbish, David Jon

doi:10.1007/s00445-013-0785-3

Cited by 9 publications

(11 citation statements)

References 42 publications

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“…We suggest that the sills and debris flow deposits described here were emplaced beneath thick ice, in a similar way to the model of Smellie (2008). This is because the sills appear to have intruded along the base of the ice both prior to and during the debris flows (as they are present both beneath the subsequence, with no alteration of the overlying deposits, and in its lower parts, mostly parallel to the bedding), contradicting the models of Banik et al (2014). Furthermore, it is difficult to reconcile the apparently contemporaneous deposition of the sequence of debris flows as extensively as they are present on Sollipulli with the amount of meltwater that could be generated beneath thin glaciers.…”

Section: Sharkfin Debris Flow Subsequencecontrasting

confidence: 61%

“…The local occurrence of the lava subsequence above the hyaloclastite suggests that these lavas could have been erupted under ice, but their presence beneath the hyaloclastite subsequence in all locations where its base is exposed indicates that there was a widespread shift to conditions favourable to meltwater ponding, which we consider to be most plausibly explained by glacierisation. Additionally, the ice thickness associated with Dalsheidi-type sequences, which we consider analogous to the Sharkfin debris flow subsequence, has been disputed (Smellie, 2008;Banik et al, 2014). This is discussed in Section 4.1.3, where we suggest that the field evidence is more consistent with the model of emplacement under thick ice.…”

Section: Discussionmentioning

confidence: 81%

“…One interpretation is that they are produced by a sill intruding along the bedrock-ice interface beneath a thick temperate ice sheet, which generates sufficient meltwater to eventually float the ice sheet, causing a debris flow of hyaloclastite (erupted at the vent) beneath it (Smellie, 2008). Alternatively, Banik et al (2014) argue that these sequences are the result of eruptions beneath thin or negligible ice (supported by measurements of the volatile content of glass), with the 'sills' being lava flows that either preceded the debris flows or intruded down into and along the base of preexisting deposits. We suggest that the sills and debris flow deposits described here were emplaced beneath thick ice, in a similar way to the model of Smellie (2008).…”

Section: Sharkfin Debris Flow Subsequencementioning

confidence: 98%

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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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Section: Sharkfin Debris Flow Subsequencecontrasting

confidence: 61%

Section: Discussionmentioning

confidence: 81%

Section: Sharkfin Debris Flow Subsequencementioning

confidence: 98%

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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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“…The subsurface stratigraphy of Iceland mainly consists in a succession of hyaloclastite formations and lava flows (Weisenberger and Selbekk 2009;Banik et al 2014) sometimes intersected by basalt intrusions (Lonker et al 1993;Mortensen et al 2014). The thickness of individual layers is variable and irregular (Watton et al 2013), varying between a few meters and a few hundred meters (Alfredsson et al 2013).…”

Section: Rock Formationsmentioning

confidence: 99%

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

2015

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Geological field observations evidence that active and fossil Icelandic hydrothermal systems are typically embedded into an intercalation of almost completely altered and nearly unaltered volcanic rock layers. We investigated the reasons for this finding with help of geochemical reaction path calculations, by studying the mineralogical evolution of contrasting lithofacies-basalt flows and hyaloclastites at various temperatures and pressures, different recharge water composition, and gas content. From this study, we conclude that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are sufficient to explain the different extents of alteration as observed in field studies. In addition, we present a generalized kinetic model to estimate the alteration time of glassy fragments in hyaloclastite as a function of grain size, surface roughness, and temperature. This time was found to be rather short, ranging from a few hours to a few years.

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“…; Banik et al . ). Avoiding the confusion, and for simplicity, we collectively use the term ‘subaqueous bombs’ for fluidal clasts of explosive origin in the Sawasaki pyroclastic rocks (Fig.…”

Section: Sawasaki Basaltmentioning

confidence: 97%

Pillow lava and spasmodic submarine fire fountaining in the middle Miocene marginal basin, Sado Island, Japan

et al. 2014

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The Sawasaki basalt unit of the Ogi Basalt Member is a middle Miocene submarine volcano formed in a marginal basin, cropping out on the coast of the Ogi Peninsula, Sado Island, Japan. It is approx. 100 m thick, more than 4 km wide, and is composed of pillow lavas (Sawasaki pillow lava) and overlying fire fountain deposits (Sawasaki pyroclastic rocks). The Sawasaki pillow lava is a pile of nearly-horizontal lava flows. Massive sheet lavas and lava pods grade into pillow lavas. The flat surfaces of the sheet lavas suggest that they spread over a summit plain. The margin of the Sawasaki pillow lava is dominated by thin elongated pillow lobes (20-30 cm across) dipping at 45-60°, contrast with the large pillows (40-100 cm across) in the core. The proximal lithofacies of the Sawasaki pyroclastic rocks is scoria agglomerate which is composed of tens of stratified beds. Individual beds have a range of clast sizes and abundance of subaqueous bombs (sometimes up to >70%), which suggests that they were formed by submarine spasmodic fire fountain eruptions. Progressive aggradation from a turbulent flow allowed settling of well-preserved fluidalshaped subaqueous bombs in a fines-depleted matrix. The basal layer shows lamina, scour and imbrication of scoria clasts. The thick scoria agglomerate beds with large subaqueous bombs, derived from energetic fire fountains, were emplaced during transition to higher degrees of hydrovolcanic fragmentation. Alternating scoria lapilli tuff and tuff beds in the distal area may represent the coupled topset and foreset beds formed by deposition from dilute, turbulent flows, and cascading of volcanic debris from the crest of the volcanic hill.

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Magma–ice–sediment interactions and the origin of lava/hyaloclastite sequences in the Síða formation, South Iceland

Cited by 9 publications

References 42 publications

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

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

Differential alteration of basaltic lava flows and hyaloclastites in Icelandic hydrothermal systems

Pillow lava and spasmodic submarine fire fountaining in the middle Miocene marginal basin, Sado Island, Japan

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