Mineralogy and Geochemistry of Mississippian and Devonian Black Shales at the Northern Margin of the Rhenohercynian Zone

Different black shale sequences occurring in the Devonian and Mississippian at the northern margin of the Rhenish Massif and the Ardennes have not been considered economically interesting targets so far. Due to their high thermal maturity, all oil potential has been exhausted. Nevertheless, some of these shales are still within the gas window. Therefore, these sequences may well act as economically feasible gas shales in the future. To evaluate the shale gas potential, extensive measurements on these black shales have been performed, including mineralogical investigations, analysis of organic and inorganic geochemical composition, as well as vitrinite reflectance measurements. Next to gathering information on Devonian and early Mississippian black shale sequences, this study mainly focused on the marine, organic-rich “Hangende Alaunschiefer” (Upper Alum Shale) in Germany and the Belgian “Chokier Formation” of late Mississippian age. Results of these extensive measurements revealed that especially the properties of the Upper Alum Shale and the Chokier Formation are similar to producing gas shale formations in the USA. Therefore, these sequences may become an important target for future shale gas exploration in Europe.