Fig. 9

Comparison of metamorphosed sandstones of different units of the Modereck nappe system: a fine-grained, phengite- and quartz-rich meta-arkose of the Wustkogel Formation. b and c thin section images with parallel and crossed polarizers, respectively, of a similar lithology to a from the Wustkogel Formation (sample PG75, 47.00636°N 12.92570°E). Note that this rock consists mainly of phengite and quartz, with only a few larger albite-clasts. d a relatively coarse-grained arkosic gneiss from the Trögereck Nappe. e and f thin section images with parallel and crossed polarizers, respectively, of a similar lithology to d from the Trögereck Nappe (sample PG78, 47.01618°N 12.92424°E). The rock mainly consists of phengite, quartz and relatively large albite clasts or blasts. Additionally, few biotite grains are present, e.g., at the tips of the elongated feldspar crystals. No carbonate minerals are present in this rock, which is why it is grouped with the Trögereck Gneiss (basement of the Trögereck Nappe)