The hydrological balance of the Black Sea is governed by riverine input and by the exchange with the Mediterranean Sea through the shallow Bosporus Strait. These sources have distinctly different oxygen isotope (δ18O) signatures. Therefore, the δ18O of Black Sea water directly reflects the presence or absence of a connection with the Mediterranean Sea, as well as hydrological changes in the vast watersheds of the Black and Caspian seas. However, the timing of late to middle Pleistocene water intrusions to the Black Sea is poorly constrained in sedimentary sequences. Here we present a stacked speleothem δ18O record from Sofular Cave in northern Turkey that tracks the isotopic signature of Black Sea surface water, and thus allows a reconstruction of the precise timing of hydrological shifts of the Black Sea. Our record, which extends discontinuously over the last 670,000 years, suggests that the connection between the Black Sea and Mediterranean Sea has been open for a significant period at least twelve times since 670,000 yr ago, more often than previously suggested. Distinct minima in the Sofular δ18O record indicate at least seven intervals when isotopically depleted freshwater from the Caspian Sea entered the Black Sea. Our data provide precisely dated evidence for a highly dynamic hydrological history of the Black Sea.
|Original language||English (US)|
|Number of pages||4|
|State||Published - Apr 2011|
Bibliographical noteFunding Information:
Support of the Swiss National Science Foundation (grant PP002-110554/1 to D.F.), the US National Science Foundation (ESH 0502535 to R.L.E. and H.C.), the Gary Comer Science and Education Foundation (CP41 to R.L.E.) and Istanbul Technical University (grant ITU-BAP-332491 to O.T.) facilitated this work. We would like to thank P. C. Tzedakis and M. Siddall for providing their data and for helpful discussions.
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