Application of cathodoluminescence to magmatic quartz in a tin granite – case study from the Schellerhau Granite Complex, Eastern Erzgebirge, Germany

Abstract

A model of the cooling history of tin-bearing granitic magma forming the Schellerhau granites (Eastern Erzgebirge, Germany) is shown on the basis of quartz textures. Similar grain size, similar grain habit and correlatable growth textures of phenocrysts in different granite varieties give proof of a common crystallization history before the melts of the Schellerhau granite varieties were intruded. Four nucleation events occurred during crystallization in different crustal levels between about 20 and 1 km depth. The parental melt of the Schellerhau granites is interpreted to have contained<2.5 wt% H₂O originally. The water content of the melt during the subvolcanic intrusion stage amounted to more than 5 wt% and characterizes highly evolved residual melts that enable the formation of tin deposits. This study contributes to a better understanding of the development and behaviour of fractionated tin-bearing granitic melts, and links quartz cathodoluminescence (CL) with microanalytical studies.