Formation and paleoclimatic interpretation of a continuously laminated Sapropel S5: A window to the climate variability during the Eemian interglacial extreme in the Eastern Mediterranean

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Sapropelic layers are widespread in the Eastern Mediterranean Basin and have been subject to numerous studies on past climatic variability at the interface between high- and low-latitude climates, and on the interplay between biological production, bottom-water anoxia, and enhanced organic matter preservation. Knowledge on mechanisms and environment during the sapropel formation from laminated sections, providing quantitative estimates of productivity and highest temporal resolution on these processes, is still limited by the small number of incomplete, only partially laminated intervals available. Here, we propose to study a suite of complete, diatom-rich, continuously laminated (varved) sections of sapropel S5 of the Eemian period (~119-124 kyr BP). Continuous XRF-scanning, electron microscopic imagery (secondary and backscatter electron) and geochemical microanalysis (energy-dispersive X-ray analysis) techniques on resin-impregnated and frozen sections will be used to identify the composition of individual laminae and to quantify their spacing and frequency on annual to centennial timescales. The present study will provide detailed information on the lamina formation, on the nature and the scales of productivity variability, and on the chronology of possible cycles and events affecting the S5 deposition during the extreme warmth of the Eemian period. These results will also help to constrain the formation of black-shales in the geological past during oceanic anoxic events (OAEs), where records are affected by diagenetic processes. Further, we will be able to test the model of diatom mat formation as an important “functional type” of the biological pump for Si export and C drawdown from the perspective of continuous laminated diatomaceous sapropels in the Mediterranean.