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

Abstract

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.

Review of Explosive Hydrovolcanism

“…Stratovolcanoes either grow vertically or have a compound form, commonly as overlapping volcanic massifs where rising magma can be affected by external water in various ways. If volcanoes are above the snow line, glaciation can cover their summit regions hence glacio-volcanism interaction is likely to affect any volcanic eruptions during their evolution [102][103][104][105][106][107][108][109]. Lateral vent migration can produce various local hydrogeological features that can be encountered by the rising magma providing opportunities for various types of hydrovolcanism.…”

Patagonian ash on sub‐Antarctic South Georgia: expanding the tephrostratigraphy of southern South America into the Atlantic sector of the Southern Ocean

“…A,C). At present, glacier ice fills the ∼4‐km‐wide summit caldera that was formed by a late Pleistocene eruption before 68 ± 14 ka BP (Lachowycz et al ., ). The Alpehué pumice eruption marked the largest Holocene eruption of Volcán Sollipulli, forming an ∼1‐km‐wide crater straddled along the south‐west sector of the summit caldera (Gilbert et al ., ).…”

Tectonism and volcanism enhanced by deglaciation events in southern Iceland

“…Volcaniclastic interstratified tuff and basalt facies are good indicators of full or limited deglaciation episodes (Smellie, 2008), although ice thickness cannot be precisely constrained based on this lithofacies (Lachowycz et al, 2015). In the absence of dating, the development of hyaloclastite/pillow lava ridges has been considered to have mostly occurred around the time of the LGM at the ice divide (Carrivick et al, 2009; Bourgeois et al, 1998), but also during the deglaciation, especially tuya (cf.…”