Estratigrafía y petrología de los depósitos de Azulejos del borde de la Caldera de Tejeda (Gran Canaria, Islas Canarias)

Abstract

Hydrothermal alteration deposits (locally called “Azulejos") located in the eastern rim of the Tejeda Caldera (Gran Canaria, Canary Islands) have been studied from the stratigraphical and petrological points of view. The green, blue, yellow and red altered deposits are ignimbrites and surges belonging to the Trachytic-Riolitic Formation. There are, at least, four different levels of "Azulejos", separated by non-alterated welded ignimbrites. The spatial distribution of these levels indicates a temporal southward migration of the hydrothermal activity along the caldera rim and a genetic relationship with this caldera. The mineral arrangement of the altered deposits is composed of zeolites (analcime, clinoptilolite, phillipsite, heulandite and erionite), quartz, feldspars, clay minerals (smectites and illites), clorites, carbonates and halite. The stratigraphic correspondence between "Azulejos" and the Tejeda Caldera, together with the mineral arrangement of the altered deposits, points to the existence of convective hydrothermal cells (working in open systems in which meteoric water was heated) confined to the inner part of the Caldera