Abstract

The paleoenvironmental evolution of the Black Sea is closely linked to the ingression of Mediterranean seawater over the Bosporus sill after the Last Glacial Maximum. We have reconstructed the temporal and spatial development of the Black Sea suboxic chemocline, which divides oxic surface water from anoxic, sulfidic (euxinic) deep water. By combining high-resolution geochemical records of bulk parameters (carbonate, total organic carbon, sulfur), trace metals (Cu, Mo, V), and an isotopic proxy (δ56Fe) from seven sediment cores in the Black Sea, we generated a single composite geochemical core log that serves as a reference archive for the entire basin. Our proxy records reflect the changing depositional and redox conditions of the Black Sea and permit us to estimate the inflow budget of Mediterranean seawater throughout the Holocene. Our data indicate a gradual rise of the chemocline until ca. 5.3 ka, when suboxic waters flooded the shelf for the first time. Trace metal and isotopic inventories document one major descent of the chemocline since the onset of brackish/marine conditions before the present stable situation was established.

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