Dyke swarms of ultrapotassic melasyenite to melagranite porphyries from the Central Bohemian Plutonic Complex and the Šumava part of the Moldanubicum
2009
Abstract
Numerous dykes of melasyenite, quartz melasyenite and melagranite porphyries accompanied by minettes are typical for prevailing parts of the Central Bohemian Plutonic Complex (CBPC) of Variscan age and for a large part of the Šumava Moldanubicum S of CBPC. Despite of the very large area of occurrence, compositional variations of these dykes are rather narrow.
Their chemistry, contrasting with common granitoids, correspond to ultrapotassic plutonic rocks cropping out in E part of CBPC; melagranite porphyries are chemically identical with durbachitic melagranites, i.e. the “light facies“ of the Čertovo břemeno type, quartz melasyenite porphyries are very similar to the most SiO2-rich varieties of the Tábor syenitoids.