Deep-basin evidence resolves a 50-year-old debate and demonstrates synchronous onset of Messinian evaporite deposition in a non-desiccated Mediterranean

Abstract

The Messinian salinity crisis (MSC) is perceived as an environmental crisis governed by climatic and tectonic controls, affecting global oceans' salinity and shaping the Mediterranean Sea's biochemical composition. Recently drilled offshore wells in the Levant Basin retrieved a sedimentary record of the deep-basin Mediterranean MSC salt deposits and the underlying pre-evaporite unit. In this study, we have concentrated on the pre-evaporite interval and its transition into the overlying evaporites. Analysis of this data set changes the way these deposits have been perceived since the 1970s, when they were first penetrated in their uppermost part during Deep Sea Drilling Project expeditions. Using sedimentology, seismic interpretation, biostratigraphy, and astronomical tuning, we show that Messinian salt deposition in the Eastern Mediterranean began during stage 1 of the MSC. In contrast to the present paradigm, salt was deposited synchronously with gypsum in the marginal and intermediate-depth basins significantly before the 50 k.y. interval coined as the "MSC acme event", ~400 k.y. after the crisis began. Thus salt precipitation took place in a non-desiccated deep basin, having a restricted but often open connection with the Atlantic Ocean, substantially altering our understanding of the mechanisms governing the deposition of salt giants. A coeval onset of basinal halite and marginal gypsum precipitation calls for a revaluation of global-scale climatic and oceanographic models of the MSC, taking into account a much older age for the beginning of halite deposition.1 GSA Data Repository item 2018060, summary of biostratigraphy data, seismic interpretation, spectral analysis of well logs, X-ray diffraction and scanning electron microscope

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, 2005;Druckman et al, 1995;Hsü et al, 1973;Ryan, 2008;Urgeles et al, 2011), while contesting studies doubt a sea-level drawdown of this magnitude (Gvirtzman et al, 2017;Lugli, Manzi, Roveri, & Schreiber, 2015;Meilijson et al, 2018;Roveri, Flecker et al, 2014a;Vasiliev et al, 2017). In the Levant Basin, the thickness of the Messinian evaporite sequence amounts to ca.…”

“…Their conclusions are supported by cross‐plots of seismic velocities, densities and Neutron porosities from six deep‐water industry wells. (b) Meilijson et al () concluded, utilizing well data and cuttings, that halite precipitation in the Levant basin was initiated around the onset the MSC phase 1, ca. 5.97 Ma.…”

Large Sea Surface Temperature, Salinity, and Productivity‐Preservation Changes Preceding the Onset of the Messinian Salinity Crisis in the Eastern Mediterranean Sea

“…Rapidly changing surface‐water paleoenvironments, leading to oligotypic assemblages, scarcity of calcareous nannofossils, and eventually to a‐planktonic zones in foraminifera record, may in part be explained by periodically enhanced salinity (Kouwenhoven & van der Zwaan, ). Finally, astronomical tuning of the pre‐evaporitic succession showed that the MSC onset was synchronous throughout the Mediterranean (e.g., Krijgsman et al, ; Manzi et al, ; Meilijson et al, ). However, the salinity changes accompanying the way into the MSC are still under debate.…”

The synthetic seismic expression of the Messinian salinity crisis from onshore records: Implications for shallow‐ to deep‐water correlations

“…On the other hand, the offshore record is mainly known through geophysical data; DSDP and ODP cores have recovered on average only a few tens of metres of the top of the deep offshore salt giant (see Lugli, Manzi, Roveri, & Schreiber, ; Roveri, Lugli, Manzi, Gennari, & Schreiber, ). Recently, well logs and cuttings made available by oil companies allowed dating of the onset of MSC and of evaporite deposition (Manzi et al, ; Melijson et al, ), and the top of the main evaporitic body in the Eastern Mediterranean (Gvirtzman et al, ). Despite these important results, on‐average low seismic resolution and scarce core data still hamper the full understanding of Messinian events, thus fuelling lively controversies and several contrasting scenarios (Roveri, Flecker, et al, ).…”