Las alteraciones silíceas de las lavas de Montaña Señalo, erupción de Timanfaya (1730-1736) (Lanzarote, Islas Canarias)

Abstract

The presence of hydrothermal alterations within the lavas of Timanfaya eruption (1730-1736), with high proportions of quartz and opal, suggests the effective circulation of hot fluids. The source of these fluids would be located under the island, where silica would be dissolved from sandstones and radiolarites, moving this way towards the surface as Si(OH) 4 colloids. Study of opal indicates the presence of Ainitial CT and C phases in the collected samples which, considering the time needed for producing this phase transformations in the diagenetic evolution of opal (10,000-50,000 years), suggests an accelerating process, probably related with either the presence of fluid circulation or weathering processes. Such circumstances are necessary for explaining the presence of such components affecting 300 years old lavas.