Spherulitic minettes from Central and Southern Bohemia

Geoscience Research Reports 37, 2004 (GRR for 2003), pages 105–106

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Abstract

Minettes with conspicuous spherulitic textures occur in the Barrandian Upper Proterozoic and Lower Paleozoic sediments N of the Central Bohemian Plutonic Complex (CBPC) of Variscan age and in some parts of the CBPC itself. As the presence of the K-feldspar spherulites indicate high degrees of undercooling during final consolidation of the minette magma, these minettes have intruded into relatively cool surrounding rocks. Absence of minettes as well as other types of E-W trending mafic dyke rocks in some granitoids of the CBPC (namely the Čertovo břemeno type of the "durbachitic" suite, the Sedlčany and Říčany granites) suggests that these relatively younger plutonic rocks intruded after significant cooling of older parts of the CBPC.