Fig. 5

Boxplots show the distribution of porosity for different stratigraphic Malm units and the classification into superior porosity units. The median porosity for most of the units seems rather low with unimodal distribution. Units Malm ζ 1, ζ 2, and ζ 4–5 overall show higher porosity values and a more bimodal distribution due to the heterogeneity of lithology and facies