Forsterit-serpentinový mramor s klinohumitem a spinelem u Chotěboře (moldanubikum; Český masiv); příklad retrográdní metamorfózy dolomitického mramoru

A body of dolomite marble near Chotěboř was found in migmatized biotite paragneiss the Moldanubicum directly on border with migmatites/orthogneisses Kutná Hora Crystalline Complex. The area underwent significant tectonic reworking rocks along Přibyslav mylonite zone. Therefore, only small relics early prograde HT/LP metamorphism at T > 650 - 700 °C were preserved this marble. They are represented by assemblage dolomite+calcite+forsterite+Zn-spinel+clinohumite ±Ba-phlogopite and rare baddeleyite. This mineral strong low-temperature retrograde (< 400 300 °C) under conditions high H2O activity (XCO2 < 0.10 0.15), which manifested almost complete serpentinization forsterite. Partial alteration clinohumite produced serpentine numerous inclusions a TiO2-mineral sphalerite. examined (ophicalcite) is lithologically mineralogically similar to marbles Strážek Moldanubicum.