Discrimination of sand dunes and loess deposits using grain-size analysis in northeastern Iran
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ORIGINAL PAPER
Discrimination of sand dunes and loess deposits using grain-size analysis in northeastern Iran Alireza Karimi 1 & Farhad Khormali 2 & Xin Wang 3
Received: 9 March 2017 / Accepted: 9 June 2017 # Saudi Society for Geosciences 2017
Abstract Identification and characterization of aeolian deposits in arid environments provide information on mechanisms of loess and sand accumulation. The objectives of this study were to (i) identify the distribution of aeolian deposits, (ii) discriminate loess and sand deposits using granulometric data, and (iii) describe the aeolian deposition in Sarakhs area, northeastern Iran. Particle size distributions of 26 surface samples were determined using a laser grain-size analyzer. Fine sand, very fine sand, and very coarse silt were dominant fractions in studied sediments, and the sum of these fractions ranged from 46.9% in loess deposits to 93.8% in sand dunes. The mean grain size (Mz) of sand dunes ranged from 3.31 to 3.54 ϕ, which gradually changed to 4.09 to 5.50 ϕ in loess deposits. Sorting, skewness, and kurtosis ranged from 0.84 to 1.94 ϕ, 0.18 to 0.49, and 0.76 to 2.38, respectively. Aeolian deposits in the area resulted in the incorporation of Hariroud River system and Kopeh Dagh Mountains for aeolian particle
* Alireza Karimi [email protected] Farhad Khormali [email protected] Xin Wang [email protected] 1
Department of Soil Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad 9177948974, Iran
2
Department of Soil Science, Faculty of Water and Soil Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 49138-15739, Iran
3
Key Laboratory of Western China’s Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, 222 South Tianshui Road, Lanzhou 730000, China
production and accumulation. Alluvial comminution in Hariroud River is suggested the main mechanism of sand and silt production and flood plain environment the main reservoir of these particles. The mountains of Kopeh Dagh act as a barrier and play a key role for sand and loess accumulation. Keywords Loess . Sand dune . Kopeh Dagh . Sorting . Skewness
Introduction Aeolian deposits are widely distributed on the earth, and grain-size parameters are the first and most important characteristics used in aeolian researches. Loess and sand dunes are silt- and sand-dominated aeolian deposits, respectively. Sand dunes occur in all climate conditions from polar to humid tropics, although the well-known aeolian sand dunes exist in desert environment in mid-latitude (Tsoar et al. 2009; Wolfe 2007). The Sahara and deserts in the Middle East, central Asia, Namibia, and China are the main active sand dunes containing areas in the world (Tsoar 2013). The great challenge during loess studies was disagreement on the presence of loess in arid environments. Due to existence of large loess deposit areas in periglacial environments, it was concluded that glacial grinding is the main mechanism of the silt production and t
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