Intra-Messinian truncation surface in the Levant Basin explained by subaqueous dissolution

Abstract

The Messinian salinity crisis (MSC) is an extreme event in Earth history during which a\ud salt giant (>1 × 106 km3) accumulated on the Mediterranean seafloor within ~640 k.y. Erosional\ud unconformities extending from the continental margins into the deep basins are key features\ud for reconstructing the MSC; however, the nature of the erosional processes and their subaerial\ud versus subaqueous origin are highly controversial. This study focuses on the top erosion\ud surface (TES) in the deep Levant Basin, which is notably flat, truncating a basinward-tilted\ud Messinian evaporitic succession. Based on high-resolution seismic surveys and wireline logs,\ud we show that (1) the TES is actually an intra-Messinian truncation surface (IMTS) located\ud ~100 m below the Messinian-Zanclean boundary; (2) the topmost, post-truncation Messinian\ud unit is very different from the underlying salt deposits and consists mostly of shale, sand,\ud and anhydrite; and (3) the flat IMTS is a dissolution surface related to significant dilution\ud and stratification of the water column during the transition from stage 2 to stage 3 of the\ud MSC. Dissolution occurred upslope where salt rocks at the seabed were exposed to the upper\ud diluted brine, while downslope, submerged in the deeper halite-saturated layer, the salt rocks\ud were preserved. The model, which requires a stratified water column, is inconsistent with a\ud complete desiccation of the eastern Mediterranean Sea

A new chronostratigraphic and palaeoenvironmental framework for the end of the Messinian salinity crisis in the Sorbas Basin (Betic Cordillera, southern Spain)

“…could belong either to a lowstand or to a transgressive systems tract of a depositional sequence bounded at its base by the MES. During all the stages of the crisis, all the Mediterranean basins (shallow and deep) show the same evolution of the Sr isotope signature, with typical depleted values of stage 3 clearly distinguishable from those of stages 1 and 2 (Gvirtzman et al, ; Manzi et al, ; Roveri, Lugli, et al, ), thus suggesting the permanence of a relative high sea level allowing the interconnections of the marginal and deep basins. Thus, the occurrence of a catastrophic return of the oceanic waters in an almost desiccated Mediterranean is in our view unlikely.…”

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

“…During this catastrophic event, the Mediterranean basins experienced cyclic hypersaline conditions and deposition of a thick evaporite series. Evidence for partial or complete desiccation has been presented in a number of studies from the Mediterranean region (Ben‐Gai et al, ; Druckman et al, ; Hsü et al, ; Ryan, ; Urgeles et al, ), while contesting studies doubt a sea‐level drawdown of this magnitude (Gvirtzman et al, ; Lugli, Manzi, Roveri, & Schreiber, ; Meilijson et al, ; Roveri, Flecker et al, ; Vasiliev et al, ). In the Levant Basin, the thickness of the Messinian evaporite sequence amounts to ca.…”

“…Seismic horizons were interpreted using seeded 2D autotracking and guided autotracking due to the decisive quality and the vastness of the dataset. In this study, we have adopted the seismic stratigraphic framework and nomenclature of Feng et al () and Gvirtzman et al () where the six Messinian seismic units, between the bottom surface/Base Salt (BS) and the IMTS, are named (from deep to shallow): ME1, ME2, MC1, ME3, MC2 and ME4 (Figure ). These units have been subject to substantial deformation both during and after the MSC, demonstrated by truncation and deformation of the IMTS (Kartveit et al, ).…”

“…Seismic stratigraphic column from the study area. Stratigraphic framework and nomenclature is based on Feng et al () and Gvirtzman et al ()…”

“…(a) Regional tectonic map of the Eastern Mediterranean. The study area marked as “*” signifies the study area from Gvirtzman et al () (b) Outline of the study area…”