Past exam of the year 2 of the earth sciences (geology) course of the University of Oxford / 2023 / Paper 1 / 6 / a

The sandstone records deposition of transported sand, followed by burial and cementation. For the Bunter setting, river channels, floodplains with channel sands and arid continental dune systems are plausible environments; a sandstone name alone does not uniquely distinguish them. Well-sorted or weakly cemented sand can retain the connected porosity and porous permeability needed for a saline aquifer.

The Zechstein evaporite suggests restricted marine basins or salinas in an arid climate, where evaporation concentrates seawater until dissolved salts precipitate. Repeated restriction and replenishment can build thick evaporite sequences, including rock salt. The Triassic limestone indicates carbonate accumulation, plausibly in warm, shallow marine settings with limited siliciclastic supply, followed by cementation. Some limestones can also form in lakes; the marine interpretation here uses the stated regional sequence.