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Investigating the deepest part of a volcano plumbing system: Evidence for an active magma path below the western flank of Piton de la Fournaise (La Réunion Island)
Author(s)
Language
English
Obiettivo Specifico
2V. Struttura e sistema di alimentazione dei vulcani
4V. Dinamica dei processi pre-eruttivi
5V. Dinamica dei processi eruttivi e post-eruttivi
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
/341 (2017)
Pages (printed)
193-207
Issued date
2017
Abstract
Peripheral diffuse degassing of CO2 from the soil occurs across the western flank of Piton de la Fournaise volcano
(La Réunion Island, Indian Ocean) along a narrow zone. In this area, carbon isotopic analysis on soil gas samples
highlights significant mixing between magmatic and organic end-members. The zones with the strongest magmatic signature (highest δ13C) overlap spatial distribution of hypocenters recorded shortly before and during volcano reactivation and allow discriminating a N135° degassing lineament, with a minimum length of 11 km and
140 ± 20 m-width. Such orientation is in accordance with that of an old dyke network along the rift zone and
with N120–130° and N140–155° lineaments related to the inheritance of oceanic lithosphere structures.
Our findings show that this N135° lineament represents a preferential magmatic pathway for deep magma transfer
below the volcano flank. Moreover, spatial distributions of recent eccentric cones indicate a well-founded possibility that future eruptions may by-pass the shallow plumbing system of the central area of the volcano, taking a lateral pathway along this structure. Our results also confirm that Piton de la Fournaise activity is linked to a laterally
shifted plumbing system and represent a major improvement in identifying the main high-risk area on the densely
populated western flank of the volcano
(La Réunion Island, Indian Ocean) along a narrow zone. In this area, carbon isotopic analysis on soil gas samples
highlights significant mixing between magmatic and organic end-members. The zones with the strongest magmatic signature (highest δ13C) overlap spatial distribution of hypocenters recorded shortly before and during volcano reactivation and allow discriminating a N135° degassing lineament, with a minimum length of 11 km and
140 ± 20 m-width. Such orientation is in accordance with that of an old dyke network along the rift zone and
with N120–130° and N140–155° lineaments related to the inheritance of oceanic lithosphere structures.
Our findings show that this N135° lineament represents a preferential magmatic pathway for deep magma transfer
below the volcano flank. Moreover, spatial distributions of recent eccentric cones indicate a well-founded possibility that future eruptions may by-pass the shallow plumbing system of the central area of the volcano, taking a lateral pathway along this structure. Our results also confirm that Piton de la Fournaise activity is linked to a laterally
shifted plumbing system and represent a major improvement in identifying the main high-risk area on the densely
populated western flank of the volcano
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article
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Investigating the deepest part of a volcano plumbing system Evidence for an active magma path below the western flank of Piton de la Fournaise (La Réunion Island).pdf
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