Identification of sand dune sources in the east Sistan, Iran by using mineralogical and morphoscopic characterization of sediments

Abstract

Sedimentation in the dune fields of the Sistan Plain of Iran is the result of deposition of fine-grained sediment downstream of the Helmand River. Due to poor adhesion and low moisture content of soil particles, and the strong renowned Levar wind, dune fields mostly of Barchan and Nebkha types are created. This study aims to assess the physical, morphological and mineralogical characteristics of surface (S) and sub-surface (S-S) sediments and their genetic relationships with the aeolian sand surface. For this purpose, 48 S and S-S sand samples were prepared from Niatak Corridor (NC) east of Sistan and were analyzed to determine their physical and mineralogical properties by dry sieving, scanning electron microscopy (SEM) and optical microscopy methods. Results show that the physical characteristics of S and S-S sand particles, such as sorting, roundness, minimum elongation projection, Riley sphericity, morphoscopic and mineralogical characteristics, have no significant difference. The study of thin sections showed that all samples generally contain quartz, feldspar, calcite, gypsum and lithic components. This confirms that the source of S sand dunes is local and consists of the buried layers of sands in the close vicinity. Therefore, the Hamoun Lake are most likely not a source of regional sands. The local existence of Yardang also supports the conclusion of this research.