Mediterranean sub-bottom giant Messinian salt as a precipitite
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We question the widely held view that the sub-Mediterranean giant salt is anevaporite deposited in a dessicated deep basin (Hsü model). Instead we suggest it to be aprecipitite (new word, as the termevaporite tends to beg the question) precipitated within a deep water saturated brine (Schmalz model). We question the validity of supposed dessication indicators (mud cracks, stromatolites, etc.). One is reminded of the 1950’s when submarine canyons and deep sea sand were falsely interpreted to mean ocean basins had dried up. Remarkable hypothesis require extraordinary proof! Precipitation better accounts for the usual draping (rather than ponding) of the salt strata, their apparent deposition on young oceanic crust, general lack of erosional redepositional unconformities and interposed beds with deep water fauna. The repeated (ca. 12 times) absolute blocking at the Gibraltar portal by tectonism of a flow equivalent to several Amazons defies the geomorphic principle that river cutting overpowers tectonic uplift. In isolated large arid basins, (e.g. Caspian Sea, Aral Sea, Dead Sea, Great Salt Lake) complete dessication, which requires zero precipitation and zero inflow, is an asymptotic end point never achievable in reality. Ground water hydrologic regimes and a paleo-Nile which flowed in from tropical rain forest are additional problems. Recent deposition (1983–85) of 4 cm of halite in the Dead Sea provides an actualistic example of precipitation. Undirectional inflow through a coral reef barrier dam at the Gibraltar portal is offered as possibly causing brine saturation in the Mediterranean 5 Ma.