Original paper

Microstructural characterisation of pseudotachylytes in quartzitic rocks by electron microscopy - first results

Bestmann, Michel; Gotze, Jenz; Cotza, Gianluca; de Wall, Helga; Goken, Mathias

Abstract

Localised fault zones (0.5-2 mm) were analysed within a quartzitic host rock (with 5-10 vol% muscovite) of the "SchneebergZug" from the AustroalpineUnit (Southern Tyrol, Italy). They typically occur in fault and injectionvein association. Flow fabrics, spherulitic/microlitic and corrosion microstructures indicate the presence of a high temperature melt and characterize these quartzitic fault zones as pseudotachylytes. Low temperature quartz microstructures in the adjacent host rock indicate ambient condition of about 250°C.