The Messinian Salinity Crisis is an event that not only led to the youngest known salt giant, but also impacted the global ocean salinity due to the mass of ions trapped in the Mediterranean Sea. Understanding its full implications requires comprehensive understanding of the events, and due to limitations in data acquisition, modeling is essential to bridge knowledge gaps.Our latest box model aims to include those processes and aspects that have been indicated to be the most influential by previous model studies. It is forced by (1) a reconstructed freshwater budget with the option to include a salinity feedback, (2) the depth of the Sstrait of Gibraltar and (3) changes in the sea level of the Atlantic. The circulation in the Mediterranean includes the exchange between the eastern and the western basin across the sill of Sicily on the horizontal level, as well as vertical exchange between two layers. The shapes of the boxes are determined by the hypsometry of the basin, which allows for realistic drawdown and refilling scenarios. The latter offers the option to test the influence of the Paratethys.To assess the validity of scenarios, the model output is compared to the volume of the known deposits as well as the cycles recorded in gypsum outcrops. An additional tracer in the model is the Sr isotope signal. Our findings highlight the importance of horizontal gradients in explaining gypsum deposits in the western basin, unlike the more uniform distribution of gypsum and halite the model produces in the eastern basin. While the onset of gypsum deposition may not necessarily differ between the basins, our results support the theory that halite precipitation began earlier in the east than in the west. This type of model will not answer all questions, but it might guide us to the new ones.

The Messinian Salinity Crisis is an event that not only led to the youngest known salt giant, but also impacted the global ocean salinity due to the mass of ions trapped in the Mediterranean Sea. Understanding its full implications requires comprehensive understanding of the events, and due to limitations in data acquisition, modeling is essential to bridge knowledge gaps.Our latest box model aims to include those processes and aspects that have been indicated to be the most influential by previous model studies. It is forced by (1) a reconstructed freshwater budget with the option to include a salinity feedback, (2) the depth of the Sstrait of Gibraltar and (3) changes in the sea level of the Atlantic. The circulation in the Mediterranean includes the exchange between the eastern and the western basin across the sill  of Sicily on the horizontal level, as well as vertical exchange between two layers. The shapes of the boxes are determined by the hypsometry of the basin, which allows for realistic drawdown and refilling scenarios. The latter offers the option to test the influence of the Paratethys.To assess the validity of scenarios, the model output is compared to the volume of the known deposits as well as the cycles recorded in gypsum outcrops. An additional tracer in the model is the Sr isotope signal. Our findings highlight the importance of horizontal gradients in explaining gypsum deposits in the western basin, unlike the more uniform distribution of gypsum and halite the model produces in the eastern basin. While the onset of gypsum deposition may not necessarily differ between the basins, our results support the theory that halite precipitation began earlier in the east than in the west. This type of model will not answer all questions, but it might guide us to the new ones.

Before the Messinian Salinity Crisis (MSC) left its imprint on the sediment record of the Mediterranean Sea in the form of evaporites, the basin had already undergone significant changes. At 7.17 Ma, a drop in delta 13C values, as well as a basin-wide shift in the abundance of benthic foraminifers, already attest to a sudden change in the Mediterranean conditions. This event coincides with an increase in the amplitude of the insolation curve. It thus stands to question whether a change in the freshwater budget or a change in the connection between the Mediterranean Sea and the Atlantic was the driver for this event. Answering this question would not only help to understand the event itself, but might also help to decipher the early dynamics of the MSC. With a computational box model, we investigate the response of the Mediterranean Sea to a varying freshwater budget for a wide range of restriction. The results then let us define scenarios in which we analyse how a gradually changing restriction would express itself in the basin dynamics. We find that the change in the freshwater budget alone cannot explain the changes that are attributed with the 7.2 event, but coupled with an increase in restriction most differences can be accounted for. Our results also show that a gradual change in restriction can provoke a non -linear response in the behaviour of the basin, which can appear abrupt when happening on a short enough timescale. Such a change would also enhance the influence of said changes in the freshwater budget. This tells us that the processes that most likely triggered the Messinian Salinity Crisis started much earlier and incrementally increased the restriction of the Mediterranean Sea.

The Central Mallorca Depression (CMD) located in the Balearic Promontory (Western Mediterranean) contains a well-preserved evaporitic sequence belonging to the Messinian Salinity Crisis (MSC) salt giant, densely covered by high- and low-resolution seismic reflection data. It has been proposed recently that the MSC evaporitic sequence in the CMD could be a non-deformed analogue of the key MSC area represented by the Caltanissetta Basin in Sicily. This presumed similarity makes the CMD an interesting system to better understand the MSC events. Physics-based box models of the water mixing between sub-basins, built on conservation of mass of water and salt, help constrain the hydrological conditions under which evaporites formed during the MSC. Those models have been widely used in the literature of the MSC in the past two decades. They have been mostly applied to the Mediterranean Sea as a whole focusing on the Mediterranean-Atlantic connection, or focusing on the influence of the Sicily Sill connecting the Western and Eastern Mediterranean Sea. In this study, we apply a downscaled version of such modelling technique to the CMD. First, we quantify the present-day volumes of the MSC units. We then use a reconstructed pre-MSC paleo-bathymetry to model salinity changes as a function of flux exchanges between the CMD and the Mediterranean. We show that a persistent connection between the CMD and the Mediterranean brine near gypsum saturation can explain volume of Primary Lower Gypsum under a sea level similar to the present. For the halite, on the contrary, we show that the observed halite volume cannot be deposited from a connected CMD-Mediterranean scenario, suggesting a drawdown of at least 850 m (sill depth) is necessary. Comparison between the deep basin halite volume and that of the CMD shows that it is possible to obtain the observed halite volume in both basins from a disconnected Mediterranean basin undergoing drawdown, although determining the average salinity of the Western Mediterranean basin at the onset of drawdown requires further investigation.

Although the Mediterranean is known for its equable climate, this does not apply on geological timescales. At the end of the Miocene, salinity of the Mediterranean Sea exceeded gypsum and halite saturation, leading to the youngest known salt giant to form in a relatively short time span. This event is called the Messinian Salinity Crisis. Insight into the exact circumstances leading to this extreme situation would increase our understanding of today’s system and how it would react to climatic changes. Some of the theories rely on a drastic change in circulation, leading to a stably stratified water column at high salinities. It is yet to be determined how realistic these ideas are. Conceptual box models can help to find answers to this. In a previous study it was already shown that a decrease in the rate of deep water formation in the margins can lead to a stratified water column. Here we used a predefined value for the overturning. In contrast, in the present study, the circulation, including the exchange through the strait of Gibraltar, is dynamically driven by density differences. By modelling stratification for various assumptions regarding the efficiency of the strait of Gibraltar, evaporation and the connectivity of the margins, this set-up ables us to get in-depth insights regarding the system in general, and the influence of climate and bathymetry on the circulation, specifically. This model brings us one step closer to an understanding of the circumstances of this extreme state of the Mediterranean Sea