Mineralogy, geochemistry and possible provenance of desert sand dunes from western Rub' al Khali area, southeastern Saudi Arabia
The Rub' al Khali desert dune sands are major constitutes of the southern part of the Arabian Peninsula. The investigated dunes in the present work are located in its western extreme where they display three major forms (seif, sigmoidal and barchan) with distinct variations in size and unique homogeneity of mineral composition. The Rub' al Khali sand dunes in its western part are placed in the craton interior and based on the contents of Quartz-Feldspars-Lithic fragments, they are originating from a recycled orogen in which intrusive, sedimentary and partly metamorphosed sources have contributed to the composition of the sands. The presence of minerals like clay minerals and amphiboles in the bulk composition of the dune sands supports the influence of granitic, granodioritic and schistose sources. They are all fine sand, moderately well sorted, nearly symmetrical to fine skewed and mostly mesokurtic. The heavy mineral fractions are dominated by a variety of amphiboles (winchite-riebeckite-richterite-arfvedsonite) in addition to cordierite.
The geochemistry of the Rub' al Khali dune sands show that the dune sands are associated with acid, felsic plutonic detritus linked to an active continental margin. Correlations between Fe2O3, SiO2, Al2O3, TiO2, MgO, and other oxides in the dune sands indicate the presence of ilmenite, magnetite and zircon in the samples. With respect to the provenance, there are two possibilities which are the Zagros Mountains in Iran and the Sahara Desert in North Africa. Orientation of linear dunes in the Rub' al Khali area is controlled by the dominant shamal (north) wind.