Holocene recurrent explosive activity at Chimborazo volcano (Ecuador)
Ice-capped Chimborazo is one of the large composite Ecuadorian volcanoes whose recent eruptive activity is poorly known. This paper presents the characteristics and the ages of a newly discovered Holocene sequence of pyroclastic deposits on the east and north sides of the cone. Lying upon a moraine...
Main Authors: | , , , |
---|---|
Format: | Text |
Language: | English |
Published: |
2008
|
Subjects: | |
Online Access: | https://www.documentation.ird.fr/hor/fdi:010044093 |
id |
ftird:oai:ird.fr:fdi:010044093 |
---|---|
record_format |
openpolar |
spelling |
ftird:oai:ird.fr:fdi:010044093 2024-09-15T18:11:46+00:00 Holocene recurrent explosive activity at Chimborazo volcano (Ecuador) Barba, D. /Robin, Claude /Samaniego, Pablo /Eissen, Jean-Philippe 2008 https://www.documentation.ird.fr/hor/fdi:010044093 EN eng https://www.documentation.ird.fr/hor/fdi:010044093 oai:ird.fr:fdi:010044093 Barba D., Robin Claude, Samaniego Pablo, Eissen Jean-Philippe. Holocene recurrent explosive activity at Chimborazo volcano (Ecuador). 2008, 176 (1 Special Issue), p. 27-35 Holocene volcanism Pyroclastic flow Phreatomagmatism Chimborazo volcano Ecuadorian andes text 2008 ftird 2024-08-15T05:57:42Z Ice-capped Chimborazo is one of the large composite Ecuadorian volcanoes whose recent eruptive activity is poorly known. This paper presents the characteristics and the ages of a newly discovered Holocene sequence of pyroclastic deposits on the east and north sides of the cone. Lying upon a moraine of the Late-Glacial period, the most complete section of similar to 4.5 m in thickness is located 5 km from the present summit crater. It consists of seven massive or diffusely stratified ash flow layers and four fallout layers interbedded with seven paleosoils. Based on held study, most flow deposits were assessed as surge layers, and six radiocarbon analyses obtained from charcoal fragments and paleosoils indicate that eruptions occurred at quite regular intervals between about 8000 and 1000 years ago. The first two and most potent events generated thick lahars over the north and west flanks of the cone. Surface textures of volcanic clasts were analysed by scanning electron microscopy. Blocky and blocky/fluidal vitric clasts indicate fragmentation during vulcanian explosions of a quite solidified shallow magma body. In addition, aggregates either cemented at a cooling stage (with surface fluidal textures), or consisting of fine particles (moss-looking aggregates), form a large part of the surge deposits. These characteristics indicate powerful explosions and intense fragmentation due to phreatic water reaching the conduit, probably from the ice-cap. Since the last eruption occurred between the early part of the 5th century (similar to AD 420) and the end of the 7th century, these results highlight that Chimborazo is a potentially active volcano. Given its dominating presence over the densely populated Ambato and Riobamba basins, and owing its large ice-cap, Chimborazo should be considered a dangerous volcano. Text Ice cap IRD (Institute de recherche pour le développement): Horizon |
institution |
Open Polar |
collection |
IRD (Institute de recherche pour le développement): Horizon |
op_collection_id |
ftird |
language |
English |
topic |
Holocene volcanism Pyroclastic flow Phreatomagmatism Chimborazo volcano Ecuadorian andes |
spellingShingle |
Holocene volcanism Pyroclastic flow Phreatomagmatism Chimborazo volcano Ecuadorian andes Barba, D. /Robin, Claude /Samaniego, Pablo /Eissen, Jean-Philippe Holocene recurrent explosive activity at Chimborazo volcano (Ecuador) |
topic_facet |
Holocene volcanism Pyroclastic flow Phreatomagmatism Chimborazo volcano Ecuadorian andes |
description |
Ice-capped Chimborazo is one of the large composite Ecuadorian volcanoes whose recent eruptive activity is poorly known. This paper presents the characteristics and the ages of a newly discovered Holocene sequence of pyroclastic deposits on the east and north sides of the cone. Lying upon a moraine of the Late-Glacial period, the most complete section of similar to 4.5 m in thickness is located 5 km from the present summit crater. It consists of seven massive or diffusely stratified ash flow layers and four fallout layers interbedded with seven paleosoils. Based on held study, most flow deposits were assessed as surge layers, and six radiocarbon analyses obtained from charcoal fragments and paleosoils indicate that eruptions occurred at quite regular intervals between about 8000 and 1000 years ago. The first two and most potent events generated thick lahars over the north and west flanks of the cone. Surface textures of volcanic clasts were analysed by scanning electron microscopy. Blocky and blocky/fluidal vitric clasts indicate fragmentation during vulcanian explosions of a quite solidified shallow magma body. In addition, aggregates either cemented at a cooling stage (with surface fluidal textures), or consisting of fine particles (moss-looking aggregates), form a large part of the surge deposits. These characteristics indicate powerful explosions and intense fragmentation due to phreatic water reaching the conduit, probably from the ice-cap. Since the last eruption occurred between the early part of the 5th century (similar to AD 420) and the end of the 7th century, these results highlight that Chimborazo is a potentially active volcano. Given its dominating presence over the densely populated Ambato and Riobamba basins, and owing its large ice-cap, Chimborazo should be considered a dangerous volcano. |
format |
Text |
author |
Barba, D. /Robin, Claude /Samaniego, Pablo /Eissen, Jean-Philippe |
author_facet |
Barba, D. /Robin, Claude /Samaniego, Pablo /Eissen, Jean-Philippe |
author_sort |
Barba, D. |
title |
Holocene recurrent explosive activity at Chimborazo volcano (Ecuador) |
title_short |
Holocene recurrent explosive activity at Chimborazo volcano (Ecuador) |
title_full |
Holocene recurrent explosive activity at Chimborazo volcano (Ecuador) |
title_fullStr |
Holocene recurrent explosive activity at Chimborazo volcano (Ecuador) |
title_full_unstemmed |
Holocene recurrent explosive activity at Chimborazo volcano (Ecuador) |
title_sort |
holocene recurrent explosive activity at chimborazo volcano (ecuador) |
publishDate |
2008 |
url |
https://www.documentation.ird.fr/hor/fdi:010044093 |
genre |
Ice cap |
genre_facet |
Ice cap |
op_relation |
https://www.documentation.ird.fr/hor/fdi:010044093 oai:ird.fr:fdi:010044093 Barba D., Robin Claude, Samaniego Pablo, Eissen Jean-Philippe. Holocene recurrent explosive activity at Chimborazo volcano (Ecuador). 2008, 176 (1 Special Issue), p. 27-35 |
_version_ |
1810449334321283072 |