RT info:eu-repo/semantics/article
T1 Deformation structures associated with the Tazo landslide (La Gomera, Canary Islands)
A1 Martín Luis, María Candelaria
A1 Casillas, Ramón
A1 Fernández, Carlos
A1 Colmenero, Juan Ramón
A1 Nuez, Julio de la
A1 García-Navarro, Encarnación
A2 Biología Animal y Edafología y Geología
K1 La Gomera
K1 Canary Islands
K1 Tazo landslide
K1 Deformation
K1 Debris avalanche
K1 Debris flow
AB Deformation structures below the basal plane of gravitational slides can provide useful information about the state of stress undergone by rocks prior to the sliding process and about the triggering forces acting at each particular sliding event. In the present work we conducted a structural analysis of the rocks below the surface of the gravitational slide of Tazo (La Gomera, Canary Islands) and determined the epigenetic processes involved in the filling of the amphitheatre. We also inferred the possible triggering phenomena related to the Tazo landslide. The rocks located below the surface of the gravitational slide of Tazo-i.e., the basaltic lava flows, sills and dikes of the Lower Old Edifice and the submarine volcanic rocks, gabbros, pyroxenites and dikes of the Basal Complex of La Gomera- are strongly deformed close to this sliding surface. The lava flows and dikes of the Lower Old Edifice are folded, with fault breccias and gouges, and locally foliated, defining the sliding surface. The dikes of the Basal Complex are also folded, and the gabbros and pyroxenites are affected by a large number of small faults. In the Basal Complex, the sliding surface is defined by a foliated granular gouge. In the damage zone, the Basal Complex rocks show an incipient fracture cleavage. The sliding amphitheatre has been filled by the debris avalanche or cohesive debris flow generated within the slide, as well as by later debris flows, hyperconcentrated flows, sheet flows, and by interspersed lava flows from the Upper Old Edifice. We suggest here that the collapse of the north-western flank of the Lower Old Edifice at Tazo could in part have been triggered by continuous magma injection, associated with the emplacement of dikes in a rift zone with an ENE-WSW direction, enhanced by the mechanical weakness of the Basal Complex unit, which was affected by hydrothermal metamorphism under greenschist facies conditions and by the displacement along the Montaña de Alcalá and Guillama normal faults, which are deeply entrenched in the altered rocks of the Basal Complex.
YR 2010
FD 2010
LK http://riull.ull.es/xmlui/handle/915/36249
UL http://riull.ull.es/xmlui/handle/915/36249
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DS Repositorio institucional de la Universidad de La Laguna
RD 09-nov-2024