<p>The reservoir quality of siliciclastic sandstone bodies is of utmost importance not only for the hydrocarbon industry but increasingly also for assessing the geothermal potential of deep subsurface reservoirs and ultimately for geothermal production. Reservoir quality is a function of the depositional facies, the size and architecture of the reservoir bodies, and the post-depositional diagenetic processes. In particular burial diagenesis modifies the original petrophysical properties. The combination of sedimentary structures and diagenetic modifications results in a wide range of porosity and permeability typical for most sandstone formations. Also the studied Triassic Bunter sandstones in the Hessian and Thuringian Basins in central Germany show significant variability in the reservoir properties down to the scale of individual laminae. Bedding and internal lamination and cross lamination of sandstones are marked by differences in grain size and detrital composition. The sandstones have a range in detrital compositions from quartzose sandstones to lithic sandstones as two endmembers. Differences in detrital composition are further enhanced by pedogenic clay cutans around grains. The detrital composition constrained the various diagenetic processes including mechanical and chemical compaction and cementation by quartz and illite during burial. Burial diagenesis was differentially modifying the original properties of the sandstones according to variations in the detrital composition. Any differences in detrital composition lead to differences in diagenesis. Variations in the reservoir properties at bed- and laminae-scale are thus due to differential diagenesis during burial. The Bunter sandstones provide a good example of the heterogeneous distribution of detrital and diagenetic components and features and the risks involved in geothermal and other exploitation.</p> Graphical abstract <p></p>