High-amplitude water-level fluctuations at the end of the Mediterranean Messinian Salinity Crisis: Implications for gypsum formation, connectivity and global climate

The formation and dissolution of salt giants impacts ocean chemistry on thousand-million year timescales. Gypsum precipitation weathering changes the oceanic calcium concentration with implications for carbon cycle global temperatures. However, connectivity is necessarily restricted, making timing Ca2+ extraction return more uncertain. Here we reconstruct final phase gypsum Late Miocene Mediterranean Salt Giant using micropaleontology, sedimentology 87Sr/86Sr analyses most complete record preserved at Eraclea Minoa Sicily explore its climate. Precessional gypsum-marl couplets (Upper Gypsum) characterize last 200 kyrs (Stage 3) Messinian Salinity Crisis (MSC; 5.97–5.332 Ma) in both intermediate (500–1000 m) deep (>1000 basins. interbedded selenitic layers contain well-preserved calcareous nannofossil assemblages dominated by Reticulofenestra minuta, a marine species which tolerates stressful conditions. Marine water also required to explain data, describe small range ratios (0.708704–0.708813) lower than coeval water. Mass-balance calculations indicate that during precipitation, Atlantic made up ≤20% (“Lago-Mare”) mass low salinity discharge from large river systems Eastern Paratethys. This suggests episodic sulfate ions throughout MSC Stage 3. marls commonly shallow (30–100 brackish-water ostracods Paratethyan (Black Sea) origin. Marls are found marginal (<500 settings. indicates marl-deposition was not synchronous across basin, but it occurred basins base-level lowstands insolation minima margins maxima-driven highstands. These high-amplitude fluctuations exposed evaporites weathering, ponded products basin until reconnection beginning Pliocene.