Sediment transport and dispersal
The end of the Middle Eocene marked the onset of a number of processes that significantly changed the paleogeography of the Middle East. Northern Arabia and East Africa started rising, the sea retreated hundreds of kilometers northwestwards, and a huge amount of terrigenous material started entering the Levant Basin. Our study seeks to understand the sedimentary sources that had fed the Levant Basin in the Late Cenozoic, the transport and dispersal mechanisms, and particularly the cause for the significant transition from basin-wide sediment dispersal in the Oligo-Miocene (deep basin sand sheets) to nearshore accumulation since the Pliocene (Nile delta and Israeli shelf).
The origin and nature of the rapid late Tertiary filling of the Levant Basin
We present two fundamental observations. Firstly, that more than half of the Levant Basin sedimentary column accumulated within a mere ~15% of the basin's life span, that is a ~6 km thick section within 37 million years (post Mid Eocene). Secondly, that this young section first accumulated in the deep basin and only then did large amounts of sediments amass along the eastern Levant continental margin. Our analysis suggests that Africa was the dominant sediment source, though turbidity currents probably entered the basin both from south and from east.
Published paper: Steinberg, J., Gvirtzman, Z., Folkman, Y., and Garfunkel, Z., 2011, The origin and nature of the rapid late Tertiary filling of the Levant Basin, Geology, vol. 39, 355-458, DOI: 10.1130/G31615.1.
Constraining sediment transport to deep marine basins through submarine channels:
The Levant margin in the Late Cenozoic
The recent world-class gas discoveries in Early Miocene sand units offshore Israel raises the question of their origin. Apparently, the simplest explanation is to relate them to a fluvial system that arrived from Arabia at that time. This system predated the modern (Pliocene) Nile River supply and existed until captured by the Dead Sea valley. Here we challenge this traditional view and suggest that the basin was mainly fed by a proto-Nile system that transported clastic material to the North African margin and then farther east by ocean currents. In a wider view we demonstrate how numerical modeling can constrain sediment transport through submarine channels as a function of basin geometry and hydraulic conditions, and how paleogeographic knowledge can be combined with current data on World Rivers to evaluate if modeling results are plausible.
Published paper: Gvirtzman, Z., Csato, I., Granjeon, D., 2014. Constraining sediment transport to deep marine basins through submarine channels: the Levant margin in the Late Cenozoic, Marine Geology, vol. 347 p. 12–26, 10.1016/j.margeo.2013.10.010
The accretion of the Levant continental shelf alongside the Nile Delta by immense margin-parallel sediment transport
Following the termination of the Messinian salinity crisis ~5.3 million years ago, massive sedimentation in the Eastern Mediterranean Sea formed the huge Nile Delta. Alongside delta propagation, a continental shelf was accreted along the Levant margin. For several decades it was assumed that these two sedimentary structures were closely connected. Levant shelf deposits are composed of Nile-derived sediments and present-day measurements show that sand is currently being transported alongshore from the Nile Delta to offshore Israel. This study reexamines the existing paradigm about sediment transport and shelf-delta connection. We show that longshore sand transport is just a small part of a much larger process termed here margin-parallel sediment transport (MPST). Sand is transported in a nearshore shallow-water belt where marine currents are highly energetic. At the same time, shale is transported at greater depths over the deeper shelf and the continental slope where marine currents are weaker. To model the accretion of the Levant shelf alongside the Nile Delta we use a 3D, diffusion based, stratigraphic modeling tool (DionisosFlow) with a new module representing MPST. Our results show that margin-parallel transport of silt and clay
in the deeper waters accounts for the bulk of deposition offshore Israel and is responsible for the development of the Levant shelf. Moreover, though MPST has begun coevally with delta formation, massive accretion of the Levant shelf was delayed by 2–3 My. Initially, a continental shelf formed offshore Sinai, then offshore Israel, and most recently along the Lebanon coast. Our model also demonstrates the significant lithological differences observed between sedimentation in front of the Nile River mouth and along adjacent continental margin. High energy down-slope sediment transport carries sand, silt, and clay, whereas margin-parallel currents are relatively weak and carry mainly silt and clay. One exception within the margin-parallel system is the highly energetic nearshore current that transports sand. Thus, we point out, MPST is an efficient separator between shale and sand.
Published paper: Zucker, E., Gvirtzman, Z., Granjeon, D., Garcia-Castellanos, D. and Enzel, Y., 2021. The accretion of the Levant continental shelf alongside the Nile Delta by immense margin-parallel sediment transport. Marine and Petroleum Geology, 126, p.104876.
https://www.sciencedirect.com/science/article/pii/S0264817220306590?via%3Dihub