Fig. 5From: The pioneer work of Bernard Kübler and Martin Frey in very low-grade metamorphic terranes: paleo-geothermal potential of variation in Kübler-Index/organic matter reflectance correlations. A reviewStratigraphic section of the Permian to late Triassic rocks of the Silvretta nappe (Upper Austroalpine, Grisons, Eastern Switzerland) with related Kübler-Index (KI) values deciphering a hyper-thermal burial gradient. All kind of rocks could be used for the graph. The illite 10 Å-peak showed mostly peaks higher than 50 cps, except in the Hauptdolomite. The figure is modified after (Ferreiro Mählmann 1994, 1995, 2001) including data from the Prosanto Formation (open circles) measured for Meister (1999). Strongly varying KI values in bituminite and organic matter rich rock are shown in black dots. Samples from rocks of an evaporitic facies are presented with a grey filled circle Back to article page