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Stress fields associated with the growth of a large shield volcano (La Palma, Canary Islands)
Author(s) -
Fernández Carlos,
de la Nuez Julio,
Casillas Ramón,
García Navarro Encarnación
Publication year - 2002
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2000tc900038
Subject(s) - geology , subaerial , volcano , lithosphere , stress field , archipelago , shield volcano , tectonics , seismology , shield , lineament , cauchy stress tensor , paleontology , lava , finite element method , thermodynamics , oceanography , classical mechanics , physics
Measurements of dyke orientations and fault slip data have been taken in 39 stations located in the northern part of the island of La Palma (Canary Archipelago). These structures affect the materials belonging to the submarine growth stage and to the lower units of the subaerial shield volcano stage. Four sets of dykes have been distinguished (Groups I, II, III‐1, and III‐2). The two younger dyke groups (III‐1 and III‐2), with highly variable strikes, are clearly related to the subaerial growth stage. Most of the measured faults are normal. Field relationships and the use of stress inversion methods allowed us to separate three different stress tensors. Tensor 2 is associated with the dykes of Group III‐1. Given the spatial distribution of the stations with faults of tensor 2 and dykes of its coeval Group III‐1, it has been possible to obtain a map of trajectories of the maximum (S H ) and minimum (S h ) compressive stress axes in the horizontal. Comparison between this map and the results of theoretical models suggests that the stress field active during, at least, the early stages of growth of the shield volcano in La Palma (from near 1.7 Myr to, at least, 1.2 Myr ago), includes a compressive radial (volcanic) component plus a regional tensile stress of a tectonic origin. This second component might be the imprint in the Atlantic oceanic lithosphere of the Cenozoic convergence between the African and Eurasian plates.