Subsurface stratigraphy of the Sorbas basin (SE Spain) records a shallowing-upward evolution during the Messinian Salinity Crisis

This study analyses a 175 m-deep continuous drill core from the Sorbas basin (SE Spain), and correlates it with additional unpublished cores that together recover the complete Messinian stratigraphic succession. The sequence records a shallowing-upward trend, from pre-evaporitic to-post-evaporitic units. Multiple sedimentological, palaeontological and geochemical proxies indicate episodes of oxygen-depleted conditions in marginal-marine environments prior to gypsum precipitation. A progressive undersaturation and a relative sea-level fall is evidenced by the transition from selenitic to brecciated gypsum and carbonate-rich coastal facies, together with the presence of bio-induced dolomite, framboidal pyrite, and immobile-element ratios. The appearance of diverse benthic foraminifera exclusively in the third inter-evaporitic marl level reveals near-normal marine conditions within an overall trend toward basin restriction and regression. This low-salinity event is correlated regionally between Sorbas, Tabernas and Bajo Segura basins, revealing diluted marine waters during the Messinian Salinity Crisis (MSC). The presence of well-preserved foraminifera can be correlated with a resedimented foraminifera association in Zorreras Hill, suggesting an erosional event at its base. 87 Sr/ 86 Sr ratios from two samples collected in the Sorbas Member fall within the range of Primary Lower Gypsum (PLG), suggesting a PLG age of the Sorbas Member, but diverge from values from Zorreras Member, supporting a sedimentary hiatus between these two units. This study provides new constraints on the timing, lateral facies relationships and paleoenvironmental evolution of the marginal Sorbas basin during the MSC.