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Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)

Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)
Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)
The Rocche Rosse lava flow marks the most recent rhyolitic extrusion on Lipari island (Italy), and preserves evidence for a multi-stage emplacement history. Due to the viscous nature of the advancing lava (108 to 1010 Pa s), indicators of complex emplacement processes are preserved in the final flow. This study focuses on structural mapping of the flow to highlight the interplay of cooling, crust formation and underlying slope in the development of rhyolitic lavas. The flow is made up of two prominent lobes, small (< 0.2 m) to large (> 0.2 m) scale folding and a channelled geometry. Foliations dip at 2–4° over the flatter topography close to the vent, and up to 30–50° over steeper mid-flow topography. Brittle faults, tension gashes and conjugate fractures are also evident across flow. Heterogeneous deformation is evident through increasing fold asymmetry from the vent due to downflow cooling and stagnation. A steeper underlying topography mid-flow led to development of a channelled morphology, and compression at topographic breaks resulted in fold superimposition in the channel. We propose an emplacement history that involved the evolution through five stages, each associated with the following flow regimes: (1) initial extrusion, crustal development and small scale folding; (2) extensional strain, stretching lineations and channel development over steeper topography; (3) compression at topographic break, autobrecciation, lobe development and medium scale folding; (4) progressive deformation with stagnation, large-scale folding and refolding; and (5) brittle deformation following flow termination. The complex array of structural elements observed within the Rocche Rosse lava flow facilitates comparisons to be made with actively deforming rhyolitic lava flows at the Chilean volcanoes of Chaitén and Cordón Caulle, offering a fluid dynamic and structural framework within which to evaluate our data.
0258-8900
Bullock, Liam A.
c6ffb9b0-0a54-4ab2-9edb-f97280e6ce2d
Gertisser, Ralf
8b4ea978-2461-4a65-87c8-352c62e52c70
O’driscoll, Brian
a7ec52ae-e10a-4b70-9bfa-197ff5810fc0
Bullock, Liam A.
c6ffb9b0-0a54-4ab2-9edb-f97280e6ce2d
Gertisser, Ralf
8b4ea978-2461-4a65-87c8-352c62e52c70
O’driscoll, Brian
a7ec52ae-e10a-4b70-9bfa-197ff5810fc0

Bullock, Liam A., Gertisser, Ralf and O’driscoll, Brian (2018) Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands). Bulletin of Volcanology, 80 (5). (doi:10.1007/s00445-018-1222-4).

Record type: Article

Abstract

The Rocche Rosse lava flow marks the most recent rhyolitic extrusion on Lipari island (Italy), and preserves evidence for a multi-stage emplacement history. Due to the viscous nature of the advancing lava (108 to 1010 Pa s), indicators of complex emplacement processes are preserved in the final flow. This study focuses on structural mapping of the flow to highlight the interplay of cooling, crust formation and underlying slope in the development of rhyolitic lavas. The flow is made up of two prominent lobes, small (< 0.2 m) to large (> 0.2 m) scale folding and a channelled geometry. Foliations dip at 2–4° over the flatter topography close to the vent, and up to 30–50° over steeper mid-flow topography. Brittle faults, tension gashes and conjugate fractures are also evident across flow. Heterogeneous deformation is evident through increasing fold asymmetry from the vent due to downflow cooling and stagnation. A steeper underlying topography mid-flow led to development of a channelled morphology, and compression at topographic breaks resulted in fold superimposition in the channel. We propose an emplacement history that involved the evolution through five stages, each associated with the following flow regimes: (1) initial extrusion, crustal development and small scale folding; (2) extensional strain, stretching lineations and channel development over steeper topography; (3) compression at topographic break, autobrecciation, lobe development and medium scale folding; (4) progressive deformation with stagnation, large-scale folding and refolding; and (5) brittle deformation following flow termination. The complex array of structural elements observed within the Rocche Rosse lava flow facilitates comparisons to be made with actively deforming rhyolitic lava flows at the Chilean volcanoes of Chaitén and Cordón Caulle, offering a fluid dynamic and structural framework within which to evaluate our data.

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Accepted/In Press date: 29 March 2018
e-pub ahead of print date: 16 April 2018
Published date: May 2018

Identifiers

Local EPrints ID: 421695
URI: https://eprints.soton.ac.uk/id/eprint/421695
ISSN: 0258-8900
PURE UUID: b896818a-b1de-4399-b18f-cf4b4dd6489e

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Date deposited: 21 Jun 2018 16:30
Last modified: 13 Mar 2019 18:23

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