Gahnite-bearing marbles and their significance for regional classification of the eastern part of the Bohemian Massif
Gahnite-bearing marbles in the Polička Unit and in the Hraničná Group were recognized as a distinct mineralogical and geochemical type of the marbles within the Bohemian Massif, typically rich in Zn and Mn (Fe). Gahnite seems to be the important Zn-carrier. Conditions of its origin are not explained sufficiently due to the simple mineral assemblages Cal+Dol+Tr+Phl+Di and its large stability field. The likely process of gahnite formation seems to be its crystallization from Zn, released during metamorphism from carbonate minerals, under conditions of a relatively high activity of Al in metamorphic fluids. Remarkably similar features of the studied marbles - lithology, chemical and mineral compositions, similar sulphide and Fe-oxide minerals, concentration and composition of gahnite - suggest the Polička Unit is closely related to the Hraničná Group (Staré Město Unit). Consequently, the Polička Unit may be lithologically a part of the Lugicum, which includes the Hraničná Group (Staré Město Unit).
SNIP (Scopus, 2015): 0.700
IF (ISI, 2015): 1.326
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