Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands |
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Authors: | T. R. Walter V. R. Troll B. Cailleau A. Belousov H.-U. Schmincke F. Amelung P. v.d. Bogaard |
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Affiliation: | (1) MGG/RSMAS, University of Miami, 4600 Rickenbacker Cswy., Miami, FL 33149, USA;(2) Dept. of Geology, University of Dublin, Trinity College, Dublin 2, Ireland;(3) GEOMAR Forschungszentrum, Wischhofstr. 1–3, 24148 Kiel , Germany;(4) Present address: Institute of Volcanic Geology and Geochemistry, Petropavlovsk-Kamchatsky, Russia |
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Abstract: | The relationship between rift zones and flank instability in ocean island volcanoes is often inferred but rarely documented. Our field data, aerial image analysis, and 40Ar/39Ar chronology from Anaga basaltic shield volcano on Tenerife, Canary Islands, support a rift zone—flank instability relationship. A single rift zone dominated the early stage of the Anaga edifice (~6–4.5 Ma). Destabilization of the northern sector led to partial seaward collapse at about ~4.5 Ma, resulting in a giant landslide. The remnant highly fractured northern flank is part of the destabilized sector. A curved rift zone developed within and around this unstable sector between 4.5 and 3.5 Ma. Induced by the dilatation of the curved rift, a further rift-arm developed to the south, generating a three-armed rift system. This evolutionary sequence is supported by elastic dislocation models that illustrate how a curved rift zone accelerates flank instability on one side of a rift, and facilitates dike intrusions on the opposite side. Our study demonstrates a feedback relationship between flank instability and intrusive development, a scenario probably common in ocean island volcanoes. We therefore propose that ocean island rift zones represent geologically unsteady structures that migrate and reorganize in response to volcano flank instability.Editorial responsibility: T. DruittThis revised version was published online in February 2005 with typographical corrections and a changed wording. |
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Keywords: | Tenerife Rift zone Dike intrusion Volcano flank instability Constructive-destructive feedback mechanism Canary Islands |
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