Tracing Saharan dust to the Eastern Mediterranean: Integrating mineralogical and isotopic proxies with atmospheric trajectory modelling

Long-distance aeolian dust transport is fundamental in shaping dryland environments and adjacent deposition regions, influencing sediment budgets, soil development, and ecosystem functioning. The Eastern Mediterranean constitutes a key corridor for Saharan dust transport, yet multi-proxy studies linking depositional records with atmospheric transport modelling are scarce. This study presents new insights into the provenance, transport dynamics, and seasonal variability of long-range aeolian dust deposited on the island of Crete (Greece), integrating laboratory sediment analyses with simulated air-mass trajectories.

Deposition samples were collected over a 15-month period at seven sites across western Crete, complemented by analyses of local surface material and reference aerosols from North Africa. Mineralogical composition, grain-size distribution, and radiogenic isotope ratios (Nd, Pb, Sr) reveal that deposited material is dominated by long range transported Saharan dust, with only minor local contributions. The persistent presence of palygorskite, uniform silt-dominated grain-size spectra, and isotopic signatures distinct from local substrates clearly indicate a North African origin. Temporal variability greatly exceeds spatial variability, and no substantial topography-related sorting is observed across the Lefka-Ori mountain range.

Seasonal shifts in mineralogical assemblages and isotopic composition indicate changes in dominant source regions, ranging from northeastern Algeria during winter to northeastern Libya and northwestern Egypt in summer, with transitional phases in spring and autumn. Transport-related fractionation is reflected in the depletion of coarse grain-size fractions and soluble minerals such as gypsum, as well as in variable illite/kaolinite ratios, pointing to mixing of particles from multiple source areas rather than single-source contributions.

To evaluate the plausibility of these interpretations and to assess the added value of combining depositional records with atmospheric modelling, laboratory-derived provenance indicators were compared with backward trajectories calculated using the HYSPLIT model for days with increased dust concentrations in the deposition region. The comparison highlights how the integration of mineralogical and isotopic fingerprints, deposition and concentration measurements, and modelled air-mass trajectories enhances the resolution of dust source attribution beyond what each approach can achieve independently.

This combined methodological framework advances our understanding of aeolian processes in large-scale aeolian systems and demonstrates the potential of integrated proxy-model approaches for reconstructing dust dynamics, with implications for geomorphic processes, and human environment interactions in dust-affected regions.