Characterization of recent deep-sea debrites in the Eastern Mediterranean based on foraminiferal taphonomy

It is hypothesized that submarine transport of sediments down a continental slope induce physical disintegration of pristine (non-broken) foraminifera shells, and thus mass transport deposits should include a significant percentage of fragmented shells. To validate this hypothesis, we studied two gravity-cores from the Eastern-Mediterranean continental slope, offshore Israel: AM113 sampled within a landslide lobe at 848 m water depth, and AM015 located away from a landslide at 1080 m. At least one interval, ~0.5 m thick, of massive sediments hosting mud-clasds (i.e. debrite) was identified within each core. The timing of these debrites, based on biostratigraphy, oxygen isotopes and total organic carbon data, predates sapropel S1 in both cores and is contemporaneous (AM113) or slightly predates (AM015) the most recent deglaciation.

We found a noticeable increase in benthic and planktic foraminiferal shells fragmentation through the last deglaciation and up to the base of S1. This strongly-fragmented sequence is located in the debrite of AM113 but it is overlaying the debrite of AM015. Accordingly, we suggest two possible mechanisms for the increased fragmentation of foraminiferal shells in both cores: Sediment transport and turbulence related to submarine mass-transport events, or geochemical changes in the lower water column properties at the transition from MIS-2 to the Holocene.