High-resolution analysis of late Quaternary aeolianites on the southeastern Mediterranean coast of Israel

High-resolution analysis of late Quaternary aeolianites on the southeastern Mediterranean coast of Israel

Mokaya, B.L.^1,2, Roskin, J.^2,3, Koren, A.⁴, Filin, S. ⁴, Bookman, R¹.,

• Charney School of Marine Sciences, Department of Marine Geosciences, University of Haifa, Israel
• Geomorphology and Portable Luminescence Laboratory, the Leon Recanati Institute for Maritime Studies (RIMS), University of Haifa, Israel
• Department of Geography and Environment, Bar-Ilan University, Israel
• Mapping and Geo-Information Engineering, Technion - Israel Institute of Technology, Israel

 

Aeolianites ridges are petrified sand dunes deposited at low to mid-latitude coasts. The location, structure and lithification properties of aeolianite ridges is generally understood to reflect changes in sea level, strong wind power, fetch parameters, and sediment availability. The Israeli coast has a chain of both submerged and inland aeolianites ridges running parallel to the southeastern Mediterranean coastline. The aeolianites consist of discontinuous accumulations of fine-and cross-bedded Nilotic sands, differentially lithified by carbonate. Red, sandy palaeosoils divide the aeolianite units and represent periods of reduced wind power and stabilization. Previous studies present low-resolution dating and finds are poorly correlated with climatic and environmental events related to deposition or lithification.

This study describes the vertical and lateral evolution of an elongated aeolianite ridge, at first a sand dune that accumulated and lithified along the palaeo Israeli Mediterranean coast during the last glacial period. The main objective is to explore the dune development at single-bed to sand package stages in time and their relation to local environmental conditions and regional climatic trends and possible changes.

The methodology included high-resolution LiDAR scanned enriched by RGB image data of exposed sections, detailed Portable OSL analysis accompanied with OSL dating, and sedimentological characterization. Sedimentological analysis shows that aeolian accumulation occurred as discrete laminae that built-up cross-bedded sediment packages. Beds continuously alternate between loose sand to cemented ones. The loose laminae consist almost entirely of quartz grains, while the lithified laminae are dominated by calcium carbonate cement. Since cementation is parallel to the aeolian accumulation, it is proposed that this incipient lithification may represent a surficial process that occurred while the dune was still active and accumulating. It may represent microbiotic crusts activated by moisture conditions. These can serve as biomarkers for wind power and wetness duration.

POSL measurements have bright blue OSL signals (12-17 million) and very similar depletion and IRSL-OSL ratios that demonstrate sedimentological similarity that is suitable for reliable POSL profiling. POSL profiling revealed a high-resolution and in-order chronostratigraphy. This may suggest that the sand laminations represent specific wind events at a very high seasonal to even diurnal resolution. Lateral POSL results reveal a certain value range and it does not demonstrate evidence for a significant change in depositional age, while the vertical profile demonstrates a linear upwards decrease in count values. The trends also demonstrate that the quartz grains do not possess a saturated OSL signal. Upcoming OSL dating and outcrop image analysis will better constrain the accumulation rates and their possible connection to environmental and climatic drivers.