Comparison of Site 374 with Circum-Ionian Land Sections: Implications for the Messinian "Salinity Crisis" on the Basis of a "Dynamic Model"

Abstract

When compared with recent published literature, including that resulting from DSDP Leg 13, the sedimentological investigations of Leg 42A, Site 374 and the circum-Ionian land sections yield a "dynamic model" for the Mediterranean "salinity crisis" during the late Miocene. The main features of this model are: 1) Shallow basins with water depths down to 500 meters. 2) An almost continuous supply of oceanic waters and consequently a "Mediterranean" sea level matching approximately the world ocean sea level. Probable (minor) changes in the world ocean sea level, inducing (perhaps major) changes of the Mediterranean Sea level, may have caused the observed cyclicity of sedimentation. 3) A differentiation of lithofacies within the Mediterranean region mainly dictated by water depth and subaerial exposure. The subaqueous sedimentation could have been influenced by systems of currents within the basins and by a fresh water supply (seasonal precipitations and rivers). Water depths immediately before and after the Messinian were relatively shallow. Basinal subsidence, which occurred from at least Messinian time, with marked activity during the Pliocene and Quaternary, was probably about 1 meter per thousand years.

Evidence of sea level drawdown at the end of the Messinian salinity crisis and seismic investigation of the Nahr Menashe unit in the northern Levant Basin, offshore Lebanon

“…Truncation of the evaporite series has also been reported at various other elevations in the Eastern Mediterranean, e.g. in the Herodotus and Ionian basins (Fabricius, Heimann, & Braune, ; Ryan & Cita, ). Thus, the second scenario seems improbable as well, and we argue that the IMTS cannot be explained by dissolution of a stratified water column alone.…”

A record of the Messinian salinity crisis in the eastern Ionian tectonically active domain (Greece, eastern Mediterranean)

“…The Ionian sequence is unconformably overlain by Neogene and Quaternary deposits outcropping mainly in south‐eastern Zakynthos. These are similar to those of the pre‐Apulian zone, but thinner and characterized by unconformities (Dermitzakis, ; Nikolaou, ), and they consist of early Miocene clastic sediments outcropping in the Skopos area, followed by late‐Messinian marls and shales (30–100 m thick) intercalated with gypsum (Fabricius et al ., ). The early Pliocene deposits include calcareous pelagic marls (Trubi limestone) and sandstone intercalations (Kontopoulos et al ., ).…”

Neogene to Quaternary geodynamics of the area of the Ionian Sea and surrounding land masses

“…Finetti & Morelli 1973;Hinz 1974;Morelli 1975;Finetti 1981) and in the upper part have been provided by DSDP drilling (Site 374) (Fabricius et al 1978;927;Hsti & Montadert et al 1978: 175). The evaporites extend south into the area of the Sirte basin (or Sirte Rise) (Finetti & Morelli 1973;Morelli 1975).…”