The nature of transitions from dry to wet condition during sapropel events in the Eastern Mediterranean Sea

Benthic foraminifera were analyzed at high-resolution (millennial scale) along core MD84-641 (33°02′ N; 33°38′ E) recovered in the Eastern Mediterranean Sea and covering the last four climatic cycles. The succession of benthic foraminiferal assemblages shows that the decrease in oxygen content of eastern Mediterranean deep water was progressive for sapropels S8, S7, S6, S5, S4, and S3 and rapid for sapropels S10, S9 and S1. This suggests that climatic conditions conducing to the wet epochs associated with sapropels S8, S7, S6, S5, S4 and S3 were progressive, whereas they were rapid for sapropels S10, S9, and S1. However, hydrological conditions responsible for organic matter preservation events seem to be different from one sapropel to another. Benthic foraminifera did not disappear completely during sapropels S10, S8, S6, and S4, suggesting an episodic activation of deep-water convection and an instability of humid period.