Composition and Sources of Sand in the Wahiba Sand Sea, Sultanate of Oman

Abstract

The Wahiba Sand Sea in the Sultanate of Oman is composed of two physiographic units that can be roughly divided into northern and southern regions. The Northern Wahiba is predominantly a large megaridge system, whereas the Southern Wahiba mostly comprises linear dunes, sand sheets, and nabkha fields. Although the dunes of the two regions are of different ages, it has previously been hypothesized that their sands were derived primarily from the same source, namely coastal sands. However, mineralogical, geochemical, and grain–size data in this study suggest that the two regions have different sources. The Northern Wahiba sands have a high composition of mafic minerals and came primarily from local wadis that drain the adjacent Hajar Mountains. One of the prominent wadi sources is presently buried under sands of the Southern Wahiba, eliminating it as a current source of the Northern Wahiba. The Southern Wahiba sands have a more mineralogically mature, quartz–rich composition and are derived from separate sources, likely to be the Oman coast or adjacent sabkha plains. Previous researchers used carbonate sand, present throughout the sand sea, to infer that the coast was the major source of sands in the entire sand sea. However, geochemical evidence suggests that the carbonate grains in the sand sea originated from the two contrasting sources along with the other grains. Carbonate grains in the Northern Wahiba are derived from wadis that drain limestones in the Hajar Mountains whereas carbonate grains in the Southern Wahiba are probably reworked from underlying aeolianites and coastal sands.

Keywords::

• erg
• geochemistry
• mineralogy
• sand provenance
• sand sea