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Snow-contact volcanic facies and their use in determining past eruptive environments at Nevados de Chillán volcano, Chile

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Snow-contact volcanic facies and their use in determining past eruptive environments at Nevados de Chillán volcano, Chile. / Mee, K ; Tuffen, Hugh; Gilbert, Jennifer.
In: Bulletin of Volcanology, Vol. 68, No. 4, 02.2006, p. 363-376.

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@article{ec82e0a625cd4b2db0f1bea2db90015b,
title = "Snow-contact volcanic facies and their use in determining past eruptive environments at Nevados de Chill{\'a}n volcano, Chile",
abstract = "Studies of the eruptive products from volcanoes with variable ice and snow cover and a long history of activity enable reconstruction of erupted palaeoenvironments, as well as highlighting the hazards associated with meltwater production, such as jokulhlaups and magma-water interaction. Existing difficulties include estimation of ice/snow thicknesses and discrimination between ice- and snow-contact lithofacies. We present field evidence from the Cerro Blanco subcomplex of Nevados de Chillan stratovolcano, central Chile, which has erupted numerous times in glacial and non-glacial periods and most recently produced andesitic lava flows in the 1861-1865 eruption from the Santa Gertrudis cone on the northwest flank of the volcano. The main period of lava effusion occurred during the winter of 1861 when the upper flanks of the volcano were reportedly covered in snow and ice. The bases and margins of the first lava flows produced are cut by arcuate fractures, which are interpreted as snow-contact features formed when steam generated from the melting of snow entered tensional fractures at the flow base. In contrast, the interiors and upper parts of these flows, as well as the overlying flow units, have autobrecciated and blocky textures typical of subaerial conditions, due to insulation by the underlying lava. Similar textures found in a lava flow dated at 90.0 +/- 0.6 ka that was emplaced on the northwest flank of Cerro Blanco, are also inferred to be ice and snow-contact features. These textures have been used to infer that a small valley glacier, overlain by snow, existed in the Santa Gertrudis Valley at the time of the eruption. Such reconstructions are important for determining the long-term evolution of the volcano as well as assessing future hazards at seasonally snow-covered volcanoes.",
keywords = "Nevados de Chillan, snow-contact, palaeoenvironment reconstruction, Hackly jointing, columnar jointing, pseudopillow fractures, Santa Gertrudis lava, SUBGLACIAL RHYOLITE ERUPTION, COOLING BASALT, LAVA FLOWS, ICELAND, EVOLUTION, ANTARCTICA, REGION, BLAHNUKUR, PRODUCTS, HISTORY",
author = "K Mee and Hugh Tuffen and Jennifer Gilbert",
year = "2006",
month = feb,
doi = "10.1007/s00445-005-0017-6",
language = "English",
volume = "68",
pages = "363--376",
journal = "Bulletin of Volcanology",
issn = "0258-8900",
publisher = "Springer-Verlag",
number = "4",

}

RIS

TY - JOUR

T1 - Snow-contact volcanic facies and their use in determining past eruptive environments at Nevados de Chillán volcano, Chile

AU - Mee, K

AU - Tuffen, Hugh

AU - Gilbert, Jennifer

PY - 2006/2

Y1 - 2006/2

N2 - Studies of the eruptive products from volcanoes with variable ice and snow cover and a long history of activity enable reconstruction of erupted palaeoenvironments, as well as highlighting the hazards associated with meltwater production, such as jokulhlaups and magma-water interaction. Existing difficulties include estimation of ice/snow thicknesses and discrimination between ice- and snow-contact lithofacies. We present field evidence from the Cerro Blanco subcomplex of Nevados de Chillan stratovolcano, central Chile, which has erupted numerous times in glacial and non-glacial periods and most recently produced andesitic lava flows in the 1861-1865 eruption from the Santa Gertrudis cone on the northwest flank of the volcano. The main period of lava effusion occurred during the winter of 1861 when the upper flanks of the volcano were reportedly covered in snow and ice. The bases and margins of the first lava flows produced are cut by arcuate fractures, which are interpreted as snow-contact features formed when steam generated from the melting of snow entered tensional fractures at the flow base. In contrast, the interiors and upper parts of these flows, as well as the overlying flow units, have autobrecciated and blocky textures typical of subaerial conditions, due to insulation by the underlying lava. Similar textures found in a lava flow dated at 90.0 +/- 0.6 ka that was emplaced on the northwest flank of Cerro Blanco, are also inferred to be ice and snow-contact features. These textures have been used to infer that a small valley glacier, overlain by snow, existed in the Santa Gertrudis Valley at the time of the eruption. Such reconstructions are important for determining the long-term evolution of the volcano as well as assessing future hazards at seasonally snow-covered volcanoes.

AB - Studies of the eruptive products from volcanoes with variable ice and snow cover and a long history of activity enable reconstruction of erupted palaeoenvironments, as well as highlighting the hazards associated with meltwater production, such as jokulhlaups and magma-water interaction. Existing difficulties include estimation of ice/snow thicknesses and discrimination between ice- and snow-contact lithofacies. We present field evidence from the Cerro Blanco subcomplex of Nevados de Chillan stratovolcano, central Chile, which has erupted numerous times in glacial and non-glacial periods and most recently produced andesitic lava flows in the 1861-1865 eruption from the Santa Gertrudis cone on the northwest flank of the volcano. The main period of lava effusion occurred during the winter of 1861 when the upper flanks of the volcano were reportedly covered in snow and ice. The bases and margins of the first lava flows produced are cut by arcuate fractures, which are interpreted as snow-contact features formed when steam generated from the melting of snow entered tensional fractures at the flow base. In contrast, the interiors and upper parts of these flows, as well as the overlying flow units, have autobrecciated and blocky textures typical of subaerial conditions, due to insulation by the underlying lava. Similar textures found in a lava flow dated at 90.0 +/- 0.6 ka that was emplaced on the northwest flank of Cerro Blanco, are also inferred to be ice and snow-contact features. These textures have been used to infer that a small valley glacier, overlain by snow, existed in the Santa Gertrudis Valley at the time of the eruption. Such reconstructions are important for determining the long-term evolution of the volcano as well as assessing future hazards at seasonally snow-covered volcanoes.

KW - Nevados de Chillan

KW - snow-contact

KW - palaeoenvironment reconstruction

KW - Hackly jointing

KW - columnar jointing

KW - pseudopillow fractures

KW - Santa Gertrudis lava

KW - SUBGLACIAL RHYOLITE ERUPTION

KW - COOLING BASALT

KW - LAVA FLOWS

KW - ICELAND

KW - EVOLUTION

KW - ANTARCTICA

KW - REGION

KW - BLAHNUKUR

KW - PRODUCTS

KW - HISTORY

U2 - 10.1007/s00445-005-0017-6

DO - 10.1007/s00445-005-0017-6

M3 - Journal article

VL - 68

SP - 363

EP - 376

JO - Bulletin of Volcanology

JF - Bulletin of Volcanology

SN - 0258-8900

IS - 4

ER -