Zeolitas (clinoptilolita-analcima-filipsita) en depósitos piroclásticos miocenos del borde de la Caldera de Tejeda (Gran Canaria, Islas Canarias)

Abstract

This paper deals with the chemical and mineralogical composition of the Miocene blue-green tuffs (regionally called “azulejos”) from the western border of the Caldera de Tejeda (Gran Canaria). Petrographic observation, X ray diffraction, scanning (SEM) and transmission electron microscopy (TEM), thermal analysis and chemical determinations by both X ray fluorescence and EDAX microanalyser adapted to SEM allow identification of the following minerals: feldspars (mainly anorthoclase) , mica, dolomite, quartz, cristobalite, clay minerals (smectite and corrensite), and the zeolites: clinoptilolite, analcime and phillipsite. The arrangement of these minerals along with the Fe-rich dolomite and Ca-poor character of clinoptilolite support a genetic pattern of the zeolites by moderately hot waters (possible convective cells) in which meteoric waters were heated.