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

Abstract

The Messinian Salinity Crisis (MSC; 5.97–5.33 Ma) is an enigmatic episode of paleoceanographic change, when kilometer‐thick evaporite units were deposited in the Mediterranean basin. Here we use geochemical (biomarker and isotope) data to reconstruct sea surface temperature, salinity, and productivity‐preservation changes in the Mediterranean basin just before the MSC. The proxy data indicate that the Mediterranean Sea was significantly saltier and colder between 6.415 and 6.151 Ma, than between 6.151 and 5.971 Ma. Salinity decrease at 6.151 Ma seems to be a relatively fast event just preceding the inception of a warming phase that lasted almost uninterrupted until the MSC onset. The water exchange with the Paratethys could have caused, along with the African rivers, an increased freshwater supply, resulting in normal marine Mediterranean waters between 6.151 and 5.971 Ma, despite the severe restriction of marine connections with the Atlantic at that time. Sea surface temperature changes determined a sharp drop in productivity and/or preservation of organic matter, marked by deposition of calcareous marls. Productivity and preservation were relatively high and constant until 6.01 Ma. Afterward, increased influx of terrestrial organic matter and probably enhanced water column stratification prevailed. Around 5.971 Ma, modifications in aquatic versus terrestrially derived biomarkers indicate changes in organic matter influx at the MSC onset.

Paleoceanographic Perturbations and the Marine Carbonate System during the Middle to Late Miocene Carbonate Crash—A Critical Review

“…This opal burst was also associated with the worldwide enhancement of carbonate, phosphate and barium accumulation rates, the vertical extension of the oxygen minimum zones [8,69] and the body-size increase of many groups of large predatory marine vertebrates [70], such as fishes [71,72], marine mammals [73] and seabirds [74]. However, with the exception of species-specific (e.g., Orbulina universa [75]) and localized adaptations (e.g., [37,76,77]), the response of planktonic organisms in such oceanic environments is still poorly understood. Schmidt, et al [78] found a shift in size of mid to low latitude foraminiferal assemblages through the Cenozoic with extreme de-velopment towards larger sizes in the late Miocene.…”

“…During the Miocene strong variations in high-latitude climates are also observed. A gradual warming during the early to middle Miocene (24 Ma to 15 Ma) is followed by rapid cooling until the end of the Miocene [30][31][32][33][34][35][36][37]. Contemporaneously, the ice shield on Antarctica expanded considerably [38,39] and the first small-dimensioned ice sheets were initiated in the Northern Hemisphere [40][41][42][43][44][45][46], leading to the equivalent ~40-60 m sea level drop [47].…”

Key Environmental Factors Controlling Planktonic Foraminiferal and Pteropod Community’s Response to Late Quaternary Hydroclimate Changes in the South Aegean Sea (Eastern Mediterranean)

“…Environmental changes related to the different water column and/or sediment characteristics can be recorded virtually instantaneously in paleoceanographic proxy data, such as stable isotope and other geochemical ratios [22][23][24][25][26][27][28][29][30][31], and micro-fossil abundances, such as planktonic foraminifera and pteropods [15,17,28,[32][33][34][35][36]. This makes them extremely valuable for both stratigraphic correlations and paleoenvironmental/paleoclimate reconstructions [15,23,28,29,32,35,[37][38][39][40][41][42][43][44][45]. Their significance in the study of modern and past marine ecosystems in the eastern Mediterranean Sea is well underlined [20,31,[46][47][48][49][50][51].…”

“…Their significance in the study of modern and past marine ecosystems in the eastern Mediterranean Sea is well underlined [20,31,[46][47][48][49][50][51]. Particularly, they are used as indicators of temperature, salinity, density, and nutrient content of the water column, making it possible to identify past circulation through the sedimentary record [7,15,29,47,52,53] and detect long-and short-term paleoclimatic and paleoceanographic changes in the study area [6,10,12,15,16,[53][54][55] during the last glacial cycle.…”

From the Eastern Paratethys to the Pontocaspian basins

“…The Mio-Pliocene transition (Messinian-Zanclean) in the region was a time of dramatic palaeoenvironmental changes linked to regional tectonic and global climatic rearrangements. In the latest Tortonian, starting at 7.5 Ma, well-pronounced aridification and enhanced seasonality provoked restructuring of terrestrial biotic communities world-wide (Herbert et al, 2016) and has also been documented in Paratethyan and Mediterranean realms (Tzanova et al, 2015;Vasiliev et al, 2019a;Vasiliev et al, 2019b). At ~5.6 Ma, glacio-eustatic restriction of the Gibraltar gateway triggered isolation of the Mediterranean, resulting in a strong Mediterranean base level drop as a response to the disruption of the oceanic water budget.…”