Mineralogical characterisation of aeolian sands using multispectral satellite datasets: Implications for dune field evolution, Wahiba Dune Field, Oman

Abstract

The Wahiba Basin of NE Oman has been the focus of numerous studies involving satellite imagery that demonstrate the complex interactions between diverse source terrains and fluvial/marine/aeolian sediment transport pathways. Building upon previous work, our study resolves the mineralogy of the dune field and grain provenance utilising a multispectral dataset derived from visible to near-infrared and short-wave infrared bands of Worldview-3 (WV-3) and Sentinel-2, alongside select thermal infrared bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Spectral signatures identified from remote sensing were confirmed through selective surface sampling, followed by petrographic analysis, powder X-ray diffraction and grain-size analysis. We employed the spectral angle mapper algorithm (SAM) and band ratio analysis to classify the WV-3 covered megadunes, and validate our scenes with the ground sample data. The spectrally superior WV-3 dataset was resampled and compared, pixel-for-pixel, against a SAM-classified Sentinel-2 scene, providing a framework necessary to expand our observations regionally. The resulting datasets offer spatially expansive classified scenes that provide mineralogical context regionally and at the fine resolution of individual megadunes. Regional observations are mostly consistent with the spatial distribution of mineral phases previously defined across the dune field, highlighting the contemporary influx of sand with mineralogical affinities of proximal source regions that imprint locally. We challenge the prevailing hypothesis that the Al Hajar Mountains to the north of the dune field is the primary supplier of quartz, proposing instead that the siliciclastic-rich Huqf Arch in the south is a more likely contributor. The combined scales of resolution reveal contemporary megadune deflation and sediment reworking that contrasts the mineralogy of the contemporary flux, suggesting that dominant and subordinate regional wind trends were reversed during glacial periods. Our detailed mineralogical observations reveal the sensitivity of contemporary geomorphic surfaces to local sediment dynamics and highlight the value of multi-scale analysis in interpreting dune field evolution.