Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Contact of the Tanvald and Liberec granites near Jablonec nad Nisou
Abstract
The exposure of the Liberec and Tanvald granite contact near Jablonec nad Nisou reveals the intrusive relationship and relative age of both granites. This contact illustrates the interaction between hot calc-alkaline granitic magma and already consolidated alkali-feldspar granite. Their interface is occupied by younger contact rocks related to the Liberec and Tanvald granites. The mylonitization (shearing), protoclase, recrystallization reaction softening (semi-fluid state), up to total remelting of the Tanvald granite are characteristic features of these rocks. Younger age of the Liberec granite is documented by reduction of the grain size and absence of K-feldspar phenocrysts towards the contact (chilled margin), magnetization of the Tanvald granite (by thermal impact of the Liberec granite) and, last but not least, by radiometric dating.
