Aeolian and fluvial processes influence on dust storms of Hormuz Strait and Makran coastal plains (SE Iran); insight from geomorphic landforms, and sediment texture and mineralogy

The Hormuz Strait and Makran coastal plains in southeast Iran are significant sources of dust storms in south Asia due to an arid climate with a strong wind regime, low topography, poor vegetation cover, and large watersheds with available loose fine-grained sediments. However, their sedimentology, mineralogy, and geomorphic landforms are poorly studied. Granulometry and mineralogy analyses are performed on 46 samples of the coastal plains to explore the influence of aeolian and fluvial processes on the surface sediment properties of the coastal plains. The geomorphic landforms are mapped based on field observations, geological-geomorphological maps, and satellite images. The results show that the main sources of fine-grained dust are distal alluvial fans and flood plains, supratidal plains, and badlands. Calcite, quartz, and feldspar are major, and dolomite and halite are minor minerals. Calcite displays a positive relationship with grain size and eastward subtractive distribution pattern, while quartz exhibits a negative correlation with grain size and eastward additive distribution pattern. Feldspar shows almost a scatter distribution. The monotonous distribution pattern of chlorite, illite, and kaolinite as the main clay minerals is controlled by fluvial and alluvial processes. Aeolian processes influenced the eastward subtractive distribution of montmorillonite and palygorskite as minor clay minerals. The surface sediment texture and mineralogy of the Hormuz Strait coast are strongly affected by northwesterly wind and dust storms. Aeolian processes are dominated on the western Makran coast with large terrestrial and coastal sand dunes, while fluvial and alluvial processes are dominant on the eastern Makran coast with large distal alluvial fans.