Texture of Dune Sands of Najaf Dunes Field, Iraq

Abstract

This study aims to define the texture properties and morphological features of the dune sands in the Najaf dune fields in southwestern Iraq. The field exhibits three major types of dunes, primarily barchan, longitudinal, and dome dunes, and different varieties such as Nabkha, Barchanoid ridges, and sand sheets. Based on geographical location, the study area was divided into three zones, from which a large number of samples were collected in the field. Sixty-seven surface samples were taken from typical dunes in windward, crest, and leeward locations. Statistical parameters were computed using the Folk and Ward technique, and grain-size distributions were ascertained by mechanical sieve analysis. Selected quartz grains from three size fractions (2 Ø, 3 Ø, and 4 Ø) were studied for roundness and sphericity using optical microscopy, and surface microtextures were investigated using scanning electron microscopy (SEM). The results show that medium to coarse sand fractions predominate in regions (B) and (C), and fine sand predominates in the dunes of area (A). Aeolian movement under fluctuating wind energy is indicated by mostly positive skewness values, which range from fairly well sorted to moderately sorted. Grain size and roundness have an inverse connection, according to roundness analysis, but sphericity values mostly fall into spherical to extremely spherical classes. A variety of microtextures, such as conchoidal cracks, V-shaped percussion imprints, bulbous edges, and varying surface relief, are revealed by SEM examinations., These features show that the Najaf dunes are comparatively young and are the result of both inherited river sediments and aeolian reworking, most likely from surrounding older strata and Euphrates floodplain deposits. The work offers fresh perspectives on dune formation in arid regions' transitional fluvial–aeolian ecosystems.