The evaporites of the Realmonte salt mine (Sicily, Italy) are important archives recording the most extreme conditions of the Messinian Salinity Crisis (MSC). However, geochemical approach on these evaporitic sequences is scarce and little is known on the response of the biological community to drastically elevating salinity. In the present work, we investigated the depositional environments and the biological community of the shale–anhydrite–halite triplets and the K–Mg salt layer deposited during the peak of the MSC. Both hopanes and steranes are detected in the shale–anhydrite–halite triplets, suggesting the presence of eukaryotes and bacteria throughout their deposition. The K–Mg salt layer is composed of primary halites, diagenetic leonite, and primary and/or secondary kainite, which are interpreted to have precipitated from density-stratified water column with the halite-precipitating brine at the surface and the brine-precipitating K–Mg salts at the bottom. The presence of hopanes and a trace amount of steranes implicates that eukaryotes and bacteria were able to survive in the surface halite-precipitating brine even during the most extreme condition of the MSC.

Graphical abstract

中文翻译：

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西西里岛墨西拿盐岩和钾镁盐的生物标志物记录和矿物成分

Realmonte盐矿（意大利西西里岛）的蒸发物是重要的档案，记录了墨西尼盐度危机（MSC）的最极端条件。但是，对这些蒸发序列的地球化学方法很少，而且对生物群落对急剧提高盐度的反应知之甚少。在目前的工作中，我们研究了在MSC峰期沉积的页岩-硬石膏-卤石三重态和K-Mg盐层的沉积环境和生物群落。在页岩-硬石膏-卤石三重态中都检测到了hop烷和甾烷，这表明真核生物和细菌在其整个沉积过程中都存在。K–Mg盐层由主要的卤石，成岩的莱昂石以及主要和/或次要的Kainite组成，它们被认为是从密度分层水柱中沉淀出来的，表面是盐酸盐沉淀的盐水，而底部是盐水沉淀的K-Mg盐。hop烷和痕量的甾烷的存在暗示真核生物和细菌即使在最极端的MSC条件下也能够在表面盐酸盐沉淀的盐水中生存。

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