Optical properties of organic matter in Devonian and Lower Carboniferous black shales in the northern Drahany Upland


Authors: Franců E

Published in: Bulletin of Geosciences, volume 75, issue 2; pages: 115 - 120;

Keywords: kerogen, vitrinite reflectance, Drahany Upland, very low-grade metamorphism, paleotemperature,

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Black shales and shaly intercalations in carbonates were investigated in Konice-Mladeč area in the northern Drahany Upland. Reflectance of vitrinite-like macerals was measured in plane-polarised light. Two types of macerals were observed in the polished surfaces, representing a vitrinite-like kerogen of higher anthracite rank (Rmax = 3.3-6.0 %) and a strongly bireflectant kerogen with higher maximum reflectance (Rmax = 6.0-9.3 %) of meta-anthracite rank. Thermal maturity is similar in all stratigraphic units, depth levels and partial regions within the Konice area. The Rmax values suggest very low-grade metamorphism at temperature approximately ranging from 240 to 360 °C.