ABSTRACT
One of the largest salt deposits in the world, a salt giant, is hidden in the subsurface of the Red Sea area, including deep-sea zones. Besides, brine and salt layers blanket different parts of the Red Sea floor. In general, mass-balance calculations and geological considerations indicate that climate-driven evaporitic processes cannot form salt giants, especially those in deep marine basins. Conversely, hydration of anhydrous mafic minerals can produce effective salinization of wide sectors of the oceanic lithosphere, if the newly formed minerals, such as serpentine, assume only water in the form of OH groups and reject seawater salts. Therefore, concentrated brines and salts can be temporarily stored in the oceanic serpentinites and released during a later time by various mechanisms, giving rise to saline deposits even gigantic in size. Moreover, some of the released brines can rise to the seafloor as hydrothermal solutions or as buoyant saline diapirs. On these premises, the Red Sea salt giant and the related saline vents may have a serpentinite origin, consistent with geophysical indications of diapiric structures in the sub-surface and occurrences of ultramafic rocks in the region, particularly at Zabargad Island.
