Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Geochronology of the Melechov granite massif
Abstract
The Melechov granite massif represents the northernmost part of the Variscan Moldanubian (South Bohemian) pluton. It consists of four granite types, which, according to geological investigations, intruded in the following order: (i) Lipnice fine-grained biotite>muscovite Th-rich locally deformed granite, (ii) Kouty fine-grained biotite>muscovite granite, (iii) Melechov coarse-grained two-mica granite, with transition to the (iv) Stvořidla fine-grained two-mica granite. No geochronological data of the massif are available today. We performed 48 high-precision microprobe analysys of Th, U and Pb in monazite from all granite types. The chemical ages of all samples fall into the range of 313-317 Ma; weighted average method (Ludwig 1997) giving 95% confidence interval. This age is about c. 10 Ma younger than the age generally accepted for the southern (Austrian) part of the Moldanubian pluton (327-328 Ma, Gerdes et al. 2003). Deformed domain within the Lipnice granite contains additional younger population of monazite aged 308 Ma. This age may be attributed to deformation during the late-Variscan extensional regime.
