Sensitivity of the thermohaline circulation during the Messinian: Toward constraining the dynamics of Mediterranean deoxygenation

• DOI: 10.1016/j.dsr.2023.104217
• Publication Date: 2023-12-21T17:52:12Z
• Authors: A.M. Mancini; R. Gennari; F. Lozar; M. Natalicchio; G. Della Porta; D. Bernasconi; L. Pellegrino; F. Dela Pierre; L. Martire; A. Negri
• Keywords: Sapropel

During the Messinian, sensitivity of Mediterranean Basin to ecosystem perturbation was enhanced in response progressive restriction water exchange with Atlantic Ocean. The widespread deposition organic-rich layers (i.e. sapropel) during Messinian testifies carbon and oxygen cycles; indeed, these sediments were deposited under conditions starvation, presumably a periodic deterioration thermohaline circulation strength. Disentangling causes, effect magnitude weakening geological past is crucial for better constraining present near-future deoxygenation dynamics region current climate warming. For this purpose, we investigate sapropel-bearing succession cropping out at Monte dei Corvi (Ancona, central Italy) mineralogical, petrographic, micropaleontological stable Carbon Oxygen isotopic analyses. We show that sapropel an increase sea surface buoyancy, which hampered thus oxygenation bottom water, turn affecting bioturbating organisms. Within lithological cycle, recovery efficient recorded by thin packstone underlying marly limestone/marlstone, record intense currents. limestone/marlstone accumulated periods primary productivity organic export bottom, promoted hypoxia but not matter preservation. infer changes resulted from variations Adriatic Deep Water formation system, controlled precession-driven climatic oceanographic changes. By integrating previously published Sea Surface Temperature (SST) new mineralogical data, Salinity (SSS) leading factor controlling deposition, minimizing role productivity. SSTs characterizing deposits are close range those projected Eastern end century In scenario, future warming will be coupled SSS increase, counteract density loss provided temperature, making abysses unlikely. However, additional forcing, such as winter heat waves eutrophication, could contribute negatively balance should considered model-based projections.