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The result is the formation of the Mediterranean Water that finally spreads into the interior of the North Atlantic forming the most prominent basin-scale thermohaline anomaly at mid-depths, the Mediterranean Salt Tongue, recognizable as a basin-scale salinity anomaly at 1000–1200 m depth through the North Atlantic (see Figure 2).
This triggered the Messinian Salinity Crisis with the formation of thick salt deposits on the former seafloor [7] and erosion of the continental slopes. [8] The Nile and Rhône carved deep canyons during this time. [4] Water levels in the Mediterranean during this time dropped by kilometres. [9]
As the deep waters sink into the ocean basins, they displace the older deep-water masses, which gradually become less dense due to continued ocean mixing. Thus, some water is rising, in what is known as upwelling. Its speeds are very slow even compared to the movement of the bottom water masses.
Most studies of formational mechanisms infer some degree of reduced deep-water circulation. Oxygen can only reach the deep sea by new deep-water formation and consequent "ventilation" of deep basins. There are two main causes of OAE: reduction in deep-water circulation or raised oxygen demand from upper level.
The NADW is a complex of several water masses formed by deep convection and overflow of dense water across the Greenland-Iceland-Scotland Ridge. [5] The circulation patterns in the North Atlantic Ocean. Cold, dense water is shown in blue, flowing south from upper latitudes, while warm, less dense water, shown in red, flows north from low ...
Mode-water eddies have a complex density structure. Due to their shape, they cannot be distinguished from regular anticyclones in an eddy-centric (focused on the core of the eddy) analysis based on sea level height. Nonetheless, eddy pumping induced vertical motion in the euphotic zone of mode-water eddies is comparable to cyclones.
The Messinian Erosional Crisis is a phase in the Messinian evolution of the central Mediterranean basin resulting from major drawdown of the Mediterranean seawater (the "Messinian Salinity Crisis"). As outlined in numerous studies, erosional events along the margins of the Mediterranean Basin during the Messinian timespan, before and during the ...
Hereby, northward moving surface water release heat and water to the atmosphere and gets therefore colder, more saline and consequently denser. This leads to the formation of cold deep water in the North Atlantic. This cold deep water flows back to the south a depth of 2–3 km until it joins the Antarctic Circumpolar Current. [27]