Conductive structures around Las Cañadas caldera, Tenerife (Canary Islands, Spain) : a structural control
Coppo, N. (University of Neuchâtel (Suïssa). Geomagnetism group)
Schnegg, P. A. (University of Neuchâtel (Suïssa). Geomagnetism group)
Falco, P. (University of Neuchâtel (Suïssa). Geomagnetism group)
Costa, R. (University of Neuchâtel (Suïssa). Geomagnetism group)

Date:	2010
Abstract:	External eastern areas of the Las Cañadas caldera (LCC) of Tenerife (Canary Islands, Spain) have been investigated using the audiomagnetotelluric (AMT) method with the aim to characterize the physical rock properties at shallow depth and the thickness of a first resistive layer. Using the results of 50 AMT tensors carried out in the period range of 0. 001 s to 0. 3 s, this study provides six unpublished AMT profiles distributed in the upper Orotava valley and data from the Pedro Gil caldera (Dorsal Ridge). Showing obvious 1-D behaviour, soundings have been processed through 1-D modeling and gathered to form profiles. Underlying a resistive cover (150-2000 Om), a conductive layer at shallow depth (18-140 Om, 250-1100 m b. g. l. ) which is characterized by a "wavy-like" structure, often parallel to the topography, appears in all profiles. This paper points out the ubiquitous existence in Tenerife of such a conductive layer, which is the consequence of two different processes: a) according to geological data, the enhanced conductivity of the flanks is interpreted as a plastic breccia within a clayish matrix generated during huge lateral collapse; and b) along main tectonic structures and inside calderas, this layer is formed by hidrotermal alteration processes. In both areas, the conductive layer is thought to be related to major structural volcanic events (flank or caldera collapse) and can be seen as a temporal marker of the island evolution. Moreover, its slope suggests possible headwall locations of the giant landslides that affected the flanks of Tenerife.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Magnetotelluric method ; Caldera ; Hydrothermal alteration ; Lateral collapse ; Tenerife
Published in:	Geologica acta, Vol. 8, Núm. 1 (Març 2010) , p. 67-82, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/188005
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/1942
DOI: 10.1344/105.000001516

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