Last Deglacial to early Holocene changes in activity of the Levant Submarine Channel, Eastern Mediterranean Sea

Submarine channels in the Levant Basin, eastern Mediterranean Sea, are prominent morphological features that provide key insights into sedimentary processes and basin evolution. These northward trending channels were formed by turbidity currents and play an important role in shaping the basin morphology and stratigraphy. The most prominent channel is the >200 km-long Levant Channel (LC), originating from the northern Sinai Peninsula margins. Yet, its present activity and the recurrence interval of turbidity-current events remain poorly constrained.

In this study we aim to address these knowledge gaps by sampling a series of downcore records along LC, combining stratigraphic and micropaleontological analyses with radiocarbon-based geochronological constraints. Piston and box cores were collected from two sites along the LC thalweg: a southern site located ~60 km offshore Tel Aviv at ~1300 m water depth, and a northern site ~45 km farther down-channel at ~1500 m water depth. Piston cores reach lengths of up to ~6.5 m, while box cores recover shorter sequences (≤0.5 m), complementing the stratigraphic record and providing high-resolution coverage of surface sediment.

Sediment in both cores are predominantly non-laminated and clastic, yielding last-glacial radiocarbon ages, with the lowermost sections exceeding the radiocarbon dating limit (>45 ka BP). Sediment in reverse stratigraphic order (i.e. a downcore decrease in sediment age) is observed in the southern core. Age reversals, together with the clastic, non-laminated facies indicate mixed sediment deposition, most likely associated with repeated turbidity-current events. Above this interval, a finely laminated sediment dated to ~9 ka BP corresponding with Sapropel S1, is observed, reflecting undisturbed hemipelagic sedimentation.

Foraminiferal assemblages independently support the radiocarbon-based age model and provide additional evidence on sediment mixing. The warm-water planktonic species Globigerinoides ruber (pink), characteristic of warm interglacial conditions, is restricted to Sapropel S1 and younger sediments, whereas the cold-water species Globorotalia scitula, typical of glacial conditions, occurs exclusively below S1. Coexistence of these species in the upper glacial interval of the northern core indicates sediment mixing. Shelf-derived benthic foraminifera (e.g., Ammonia tepida, A. parkinsoniana, Cribroelphidium vadescens and Planorbulina mediterranensis) are abundant throughout both Holocene and glacial sediments in the southern core but are largely absent from the northern core, suggesting sustained delivery of shallow-shelf material at least to the southern LC site.

In summary, the Levant Channel was active during the last glacial period, with shelf-sourced turbidites, but became largely inactive during the Holocene, with hemipelagic sedimentation prevailing. This shift reflects the impact of eustatic sea-level rise and related continental shelf widening on submarine mass transport across continental margins. Similarly, previous regional studies on submarine landslides and turbidite activity within submarine canyons along the eastern Mediterranean continental margin revealed intense mass wasting activity in the last glacial period that declined through the deglaciation and the transition to the Holocene.