Continental slope processes reflected in a Holocene multi-proxy record at the southeastern Mediterranean

Continental margins sedimentary records reveal regional climate-ocean trends and identify mass transport deposits (MTD) and reflect the regional paleoclimate and paleoseismicity. This study used two radiocarbon-dated piston cores collected from the shelf edge (122 m) and mid-slope (588 m) offshore Israel at the southeastern Mediterranean Sea. CT scanning showed Holocene sediment evolution, capturing a shift in grain size and geochemistry, while detecting MTD units. The core from the shelf edge recorded the post glacial sea level flooding at 10-11 ka BP, with early Holocene sediments marked by coarser grains, high biogenic material, and abundant foraminifera. Sapropel S1, dated to 6-9 ka BP, is characterized by low Ti/Al, high Si/Al, and high TOC, reflecting increased Nile discharge and precipitation in the source region.

Benthic foraminifera disappearance in the slope core indicated bottom water anoxia, interrupted by re-oxygenation linked to the ~8.2 ka BP cold event. Toward the mid-Holocene, increased Ti/Al and Fe ratios indicate higher weathering rates in the Nile watershed due to reduced rainfall and vegetation, correlating with regional aridification caused by orbital changes.

Four MTD units with higher bulk density and reduced porosity were accompanied with higher Ca/Fe ratios. Radiocarbon dates within these units indicated the deposition of recycled older sediments from the early Holocene, while the mass transport events occurred between 6.2 and 1.8 Ka BP. Distinct changes are also observed in the benthic foraminifera taxonomy in association with the MTD including the total number of individuals per gram dry sediment (BF/g), species richness, dominance, and species composition. Furthermore, within all the MTD units a noticeable increase in broken BF shells and older radiocarbon ages, which indicate on recycled sediment turbulent mass transport.