A new sedimentary record from the Tabernas Basin: Implications for the Messinian Salinity Crisis in the Western Mediterranean

The Tabernas Basin (SE-Spain), renowned for its Tortonian turbidites, also records thick Messinian successions (>200 m) that offer valuable insights into the Messinian Salinity Crisis (MSC). Yet, the stratigraphic correlation of the Tabernas sediments with the classic successions of the nearby Sorbas Basin remains unclear. This study presents a composite stratigraphic section (named Yesón Alto) that covers the pre-evaporitic, syn-evaporitic, and supra-evaporitic stages of the MSC recorded in Tabernas Basin, offering detailed paleoenvironmental and chronostratigraphic characterization. We provide new constraints on the connections between two marginal basins of the Betic Cordillera and on the paleoenvironmental changes that took place in the Western Mediterranean during the MSC. During the Late Messinian pre-evaporitic phase, siltstones and shales alternating with distal turbidites recorded shifts between warm-oligotrophic and cold-eutrophic planktonic foraminiferal assemblages, indicating the influence of precession-driven climatic fluctuations on the water column. Progressive basin restriction led to the development of an incipient hybrid carbonate shelf, subjected to significant siliciclastic influx. 16 key planktonic foraminifera bioevents and a magnetic reversal (C3An.1n to C3r at 6.035 Ma) have been identified and correlated with the astronomically calibrated cycles of the Sorbas Basin, suggesting the possible synchronous onset of the MSC in both basins. The evaporitic stage in Tabernas is represented by four selenitic gypsum beds intercalated with siliciclastic and carbonate deposits. Facies analysis and gypsum isotopic compositions (δ34Ssulfate and δ18Osulfate) suggest that evaporites represent the initial cycles of the Primary Lower Gypsum (PLG) of the MSC Stage 1 in the Mediterranean. Below gypsum bed PLG 4, an inter-evaporitic level rich in marine fauna indicates the episodic re-establishment of near-normal marine conditions after periods of evaporite precipitation. The Supra-evaporitic unit, comprising deltaic-fluvial conglomerates and sandstones, reflects a regional regressive trend and marks the continentalization of the basin's margins. The progradation of these continental deposits over the evaporitic basin was favored by an eastward uplift trend in the Betic Cordillera, ultimately leading to exposure of the Tabernas Basin before or during Stages 2 and 3 of the MSC. The paleoenvironmental evolution of the Tabernas Basin indicates that marine connections with the Sorbas Basin persisted before and during the early MSC and that tectonics associated with climatic factors played a key role in the evolution of its sedimentary systems.

This research was funded by the Spanish Ministry of Science and Innovation (MCIN)/State Research Agency of Spain (AEI)/10.13039/501100011033 (project number PID2020-118999GBI00), MCIN/AEI/10.13039/501100011033/European Union NextGenerationEU/PRTR (project number CNS2023–145382) and the Agència de Gestió d'Ajuts Universitaris i de Recerca (grant to the Consolidated Research Group Geologia Sedimentària 2021 SGR 00349). GKLO acknowledges the FPI PhD grant number PRE2021-098107, JL the FI PhD grant number 2023 FI-1 00779 and NSR the FI-SDUR PhD grant number 2022 FISDU 00349.