Zeolites and palygorskite as weathering products of pillow lava Curaçao

Abstract

Infillings between pillows in the lavas of Curaçao consist of zeolites, notably offretite, as well as the clay minerals palygorskite and smectite. The material is dissected by veins of analcite. The zeolites have been formed from the glassy crust ofthe pillow lava upon subaerial weathering in a dry and hot climate creating a pseudo-closed system. Under these conditions, hydrolysis of the glassy basaltic material generates a saline alkaline environment favourable for zeolite formation. Behind the weathering front the altered material will be exposed to gradually less saline and less alkaline interstitial fluid and the zeolites are transformed to palygorskite. Next, at a still greater distance, palygorskite is transformed to smectite. Analcite is precipitated from a brine formed by evaporation of the interstitial fluid in fissures.