Depositional and grain-scale controls on sandstone heterogeneity in arid continental settings: The Dutch Upper Rotliegend Group

Depositional processes and early grain-scale properties exert a primary control on compositional heterogeneity and diagenetic evolution in sandstone bodies, yet their relative influence at the field scale remains difficult to quantify. As a result, regional petrographic datasets that explicitly link spatial variability in grain attributes and authigenic mineral assemblages to depositional environments are still limited. This study presents a field-wide, quantitative petrographic analysis of the Slochteren Formation of the Upper Rotliegend Group in the Groningen area (the Netherlands), which provides exceptional subsurface coverage and stratigraphic continuity. Petrographic data from fifteen wells are used to define spatial trends in detrital composition, grain size and sorting, and cement distribution, and to relate these patterns to depositional environments and structural position. A south–north transition from proximal fluvial to distal playa deposits is accompanied by smaller grain size and better sorting toward the north, whereas aeolian dune deposits are most prominent in the central and western parts of the study area. Grain size and sorting are the dominant controls on porosity and permeability, with the highest reservoir quality occurring in well-sorted, fine to medium-grained sandstone bodies of distal and aeolian origin. Compositional variations reflect both depositional and provenance controls: lithic fragments and polycrystalline quartz dominate medium and coarse southern sandstone bodies, whereas feldspar gets more common northwards and stratigraphically upward, consistent with a shift in sediment supply, likely related to either unroofing or pre-depositional reducing weathering conditions due to increasing aridity. Authigenic mineral assemblages record the combined influence of depositional texture, detrital input, and burial evolution with many cement constituents being internally sourced from local dissolution of more unstable precursor minerals. Illite and chlorite formation is closely associated with clay-coated grains in fine-grained playa facies, whereas quartz cementation is limited and controlled by burial depth, local silica availability, and inhibition by grain coatings. Dolomite locally exerts a strong control on porosity reduction. These results highlight the fundamental role of hydraulic sorting influenced by the interaction of aeolian and fluvial processes and early diagenetic processes in generating spatial heterogeneity in sandstone successions and demonstrate how grain-scale attributes control subsequent diagenetic pathways in mixed depositional systems. • Field-wide petrography reveals depositional controls on texture and composition. • Detrital composition covaries with grain size and depositional environment. • Feldspar increases stratigraphically upward, indicating changing sediment supply. • Burial diagenesis amplifies inherited depositional heterogeneity. • Authigenic minerals are largely internally derived, not externally sourced.