Arab J Geosci (2013) 6:519–527 DOI 10.1007/s12517-011-0353-0 ORIGINAL PAPER Physical properties of aeolian sediments within major dune corridor in Kuwait Ali M. Al-Dousari & Abdusalam Al-Hazza Received: 16 February 2011 / Accepted: 17 May 2011 / Published online: 24 June 2011 # Saudi Society for Geosciences 2011 Abstract A total of 212 sand samples were collected from aeolian surface sediments in a major dune corridor, northwestern Kuwait. Five main physical properties were taken into consideration in analyzing aeolian samples, namely color, shape, roundness, particle morphometry, and surface area. The analysis of quartz particles by the scanning electron microscope shows the influence of transportation on the microfeatures of individual particles. The surface deposits are dominantly unimodal and occasionally bimodal. It is obvious that coarse and medium sand are the dominant size fractions within aeolian deposits. The results according to the Munsell color system between downwind and upwind values show no variations. Also, the average percentages of roundness subclasses for upwind and downwind samples are similar (6.7%). The average values (area, equivalent diameter, perimeter, and elongation) for aeolian samples in downwind are slightly higher than in upwind and Al-Dibdibba Formation samples, but the values overlap at 1 standard deviation. The interrelationship diagrams show that the shapes of the particles within samples in the three groups are running in the same trend. In general, the northwestern (upwind) particles show more mechanical and chemical features compared with southeastern particles (downwind). The slight variation between aeolian (upwind and downwind) samples is attributed to the transportation effect of these particles. This led to a conclusion, based on the overall results of physical properties, that the coarse and medium particles (about 80% of the whole aeolian sample) are dominantly derived from local sources. A. M. Al-Dousari (*) : A. Al-Hazza Kuwait Institute for Scientific Research, P.O. Box 24885, Safat 13109, Kuwait e-mail: adousari@kisr.edu.kw Keywords Aeolian sediments . Munsell color system . Al-Dibdibba Formation Introduction Studies of individual microscopic images of sand particles show that color variations of the particles are achieved by the presence of iron oxides deposits on pits and other surface irregularities on clear or frosted quartz particles (Lancaster 1995). Wells (2002) used three-dimensional stereoscopic scatter plots to plot the three parameters of Munsell colors (hue, value, and chroma). Particle color studies were also applied to dune sand in the Strzelecki dune field of Australia (Wasson 1983), the Simpson Desert (Pell et al. 2000), the Namib sand sea (Walden et al. 1996), and Portuguese beach dunes (Guedes et al. 2009). White and Bullard (2009) claimed that dune sand become lighter in color at downwind from source area. The shape of sand particles is determined by their composition, origin, and transport history (Pye and Tsoar 1990). Experimental work done by Kuenen (1960) suggests that wind rounds 100–1,000 times faster than fluvial action. The supposedly superior rounding of aeolian sand particles results from the fact that particles transported in water possess a tightly adherent film of water which serves to protect them from impact (Goudie and Watson 1981). Krinsley and Doornkamp (1973) briefly described various mechanical and chemical features on quartz particles from different environments. Microfeatures on sand particles, including microfractures, abrasion, etching, and coating, may provide important information on paleoenvironmental history, including aeolian activity and severity of weathering inferred from etching and dissolution features. Culver et al. (1983) stated that scanning electron microscope (SEM) 520 Arab J Geosci (2013) 6:519–527 Fig. 1 The study area (box) showing the major dune corridor where sampling took place analysis performed on quartz particle surface features appears to be a reliable and statistically valid means of discriminating between samples from different environments, but the use of one microfeature to determine paleoenvironment is an invalid approach. A series of events representing a succession of environments may be recorded on a single sand particle or group of particles (Krinsley and Funnell 1965). The Brunauer, Emmett, and Teller (BET) surface area is expressed as values for a certain weight of loose sand in terms of square meter per gram measured by using isotherm Table 1 Summary of methods and number of samples Property Color Shape Particle morphometry Roundness Surface area Instrument used Minolta handheld spectrophotometer Color range (400–700 nm) All 10 10 – Eclipse Net Imaging System Area, elongation diameter, perimeter Medium sand 5 (50)a 5 (50)a 14 JEOL super prob JXA-860MX SEM 26 particles Microfeatures Coarse sand 10 (21)a 9 (21)a – Modified from Powers (1953) Roundness Coulter (SA3100) Measured items Analyzed fraction Upwind samples Downwind samples Al-Dibdibba Formation a Average number of studied particles between two brackets Coarse sand 10 (21)a 9 (21)a – Surface area (m2/gm) Medium sand 20 19 10 Arab J Geosci (2013) 6:519–527 521 Fig. 2 Modified particle shape visual comparator scheme of Powers (1953), showing numerical indices and associated descriptive terminology plot diagrams of volume against pressure and using the BET equation devised by Brunauer et al. (1938). Previous studies on aeolian sediments in the region such as Kuwait and elsewhere have focused on sedimentimophic features (Khalaf et al. 1995, Al-Dousari and Pye 2005, Al-Dousari et al. 2008), Saudi Arabia (Al-Fredan 2008), Iraq (Al-Janabi et al. 1988), Jordan (Saqqa and Attallah 2004), Qatar (Embabi and Ashour 1993), Emirates (El-Sayed 2000), and Oman (Pease et al. 1999). The physical properties of aeolian sand particles were however not been investigated. Therefore, this study aims to fill this gap of knowledge in order to model sand transport for industrial and environmental planning purposes. Study area The study area (the Huwamiliyah–Nimritayn zone) is defined by longitudes 47° and 47° 30′E, and latitudes 29° N and 29°50′ N. The study area represents a major thoroughfare for hundred of dunes and aeolian deposits from Huwamiliyah toward the southeast (Fig. 1). The total area of this zone is about 5,000 km2, representing 28.1% of the total area of Kuwait. The surface of the study area is generally slightly undulating which slopes gradually northeast with an average gradient of 2 m km−1. It comprises a relatively well articulated terrain characterized by a set of low elongated ridges trending in the northeast direction. The ridges are low, wide, with flat surfaces and are gently sloping toward the northeast. They are separated by subparallel, shallow, wide valleys and elongated depressions following the general direction of the ridges. While the maximum relief is about 8 m, the valleys cut through the Al-Dibdibba Formation which is composed of calcretic pebbly sandstone. The thickness of the Al-Dibdibba Formation increases toward the north and northwest, from a few meters in the Mutla area to a few hundreds of meters in the Huwamiliyah area. Methodology 45 40 Weight % 35 30 25 20 15 10 5 0 V.C.S C.S M.S. F.S V.F.S S Clay Grain size Fig. 3 Histograms showing the weight percentages of all aeolian samples A total of 212 sand samples were randomly collected from top 5 cm of the surface of sand drifts, nabkhas, and sand dunes within north and northwest of Kuwait. The sampling locations were determined using a global positioning system. Particle size analyses of all samples were carried out using standard sieving and sedimentation techniques (Blott and Pye 2001). There are five main physical properties which were taken into consideration in analyzing some of these samples, namely color, shape, roundness, particles morphometry, and surface area. Some of these properties were compared with Al-Dibdibba Formation (as expected source of aeolian sediments) in Mutla area where it is fully exposed. Table 1 contains a summary for the methods. 522 Arab J Geosci (2013) 6:519–527 Fig. 4 Reflectance percentage curves of upwind and downwind aeolian samples A total of 26 separate microfeatures were considered using the SEM. It was selected to represent the best overall method of analysis for describing the surface features, and derives from the early work of Krinsley and Doornkamp (1973), Bull (1981), and Culver et al. (1983). The tabulation of surface features on the quartz particles using numerical numbers or percentages was found appropriate in distinguishing between samples. Also, the roundness and angularity descriptive system of Powers (1953) was also developed in this study in order to provide more precision (Fig. 2). Results and discussion The recent aeolian deposits are dominantly unimodal (Fig. 3) and occasionally bimodal. It is obvious that coarse and medium sand are the dominant size fractions (about 80%). Particle color The average Munsell hue, value, and chroma notations upwind are approximately similar to the downwind samples, being 9.6 YR 5.77/3.9 and 9.51 YR .75/3.7, respectively. The close similarity in color between upwind and downwind samples within local scale indicates a similar origin (Fig. 4). This indication was also supported by other particle physical property results. Particle shape The average values of the four main particle shape parameters (area, equivalent diameter, elongation, and perimeter) are slightly higher in downwind with comparison to the upwind samples and Al-Dibdibba Formation samples. On the other hand, the interrelationship diagram shows that these three groups of samples are following a similar trend (Fig. 5a, b). The diagrams of area and perimeter show a high correlation between aeolian and Al-Dibdibba samples (R2 =0.95 and 0.91, respectively), and a high correlation between upwind and downwind (R2 =0.95 and 0.96, respectively). The variability between the two groups of samples is only observed within the larger range of aeolian samples between 253 and 356 μm, while it is smaller within Al-Dibdibba Formation, between 258 and 304 μm. This variability is due to the high values of Al-Dibdibba Formation samples in comparison to the aeolian samples. This data may yield important affects of wind action in modifying the aeolian samples. Quartz particle morphology The surface microfeatures of the quartz particles show that quartz has been subjected to both mechanical and chemical action (Table 2). Mechanical microfeatures Mechanical microfeatures are mainly V-shaped pits, rounded pits, crescentic pits, coalescing pits, dish-shaped depressions, sutures (curved and straight), grooves, upturned plates, meandering ridges, conchoidal fractures, striations, and stepped cleavage planes. The dish-shaped depressions and V-shaped pits are the most widely distributed features on the surfaces of the quartz particles (Fig. 6a). They are distributed on the surface of most of the studied particles in all of the samples. The particle to particle contact due to saltation gives some quartz particles a dotted surface. The size of the rounded and V-shaped pits varies from 5 to approximately 50 μm. Arab J Geosci (2013) 6:519–527 523 Fig. 5 Diagrams of area versus perimeter for Al-Dibdibba and aeolian samples (a) and for upwind and downwind (b) Quartz particles when exposed on the surface suffer from weathering and abrasion during transportation. As a result, the crescentic, rounded, and V-shaped pits dominate the surface of the chemically smoothed particles. The weathering produces adhering particles on the surface of the quartz particles and dissolution and precipitation features. Also, grooves and etching appear in the surface of some particles (Fig. 6b). Some of the quartz particles show extensive fracturing and abrasion as well as weathering (Fig. 6c). Other particles show a very distinctive smooth surface texture. Sutures and grooves appear mostly without any regularity in orientation, but some particles show great regularity. The angular quartz particles are usually rich in microfeatures such as sutures, cracks, and fractures, either linear or conchoidal. They are suppressed in visual observation due to the dominance by other microfeatures such as dish-shaped depressions and mechanical pits (Fig. 6d). Upturned plates are abundant on most of the particles. Adhering particles are rare on most of the quartz particles, but the rounded quartz particles with smooth surfaces show none or very few particles compared with those angular particles rich in microfeatures. It is concluded that some particles originally have a paleoenvir- 524 Arab J Geosci (2013) 6:519–527 Table 2 Summary for the mean occurrence of 26 surface textural features on quartz sand particles from upwind and downwind aeolian samples Microfeatures surface of some quartz particles. The deep grooving and etching take place more commonly in sutures or pits or around corners of quartz particles (Fig. 6f). Mean occurrence Upwind Downwind V-shaped pits Rounded and crescentic pits Coalescing pits Meandering ridges Curved sutures Straight suture Dish-shaped depression Conchoidal fractures Small striations Stepped cleavage planes Upturned plates Adhering particles Rounded particles Straight/curved grooves Smooth precipitation surface 5.91 5.98 0.68 2.97 3.09 2.91 6.20 2.17 1.09 1.69 7.31 1.25 7.44 5.96 1.90 5.12 5.80 0.27 2.01 2.15 2.91 3.36 1.99 0.80 1.39 6.25 1.15 6.81 5.46 1.54 Silica plastering Chemically etched V-forms Deep surface solution Dulled solution surface Oriented V-shaped pits Capping layer Quartz crystal growth Silica coating structure Irregular solution–precipitation Disintegration by solution Large-scale decomposition 4.85 1.61 3.96 0.37 3.16 0.06 0.15 1.21 6.07 2.96 2.51 3.15 1.45 3.96 0.28 2.80 0.03 0.00 0.73 5.98 4.16 2.29 Upwind and downwind variations In general, the northwestern (upwind) particles show more mechanical and chemical features compared with southeastern particles (downwind). This might indicate that the coarse quartz particles are dominantly derived from local sources (Fig. 6a). Upturned plates, dish-shaped depressions, V-shaped pits, and rounded and crescentic pits, respectively, are the dominant features in the upwind samples, while upturned plates, irregular solution precipitation, rounded and crescentic pits, and V-shaped pits, respectively, are the dominant features in the downwind samples. The dishshaped depressions were much less frequent in the downwind samples compared to the upwind samples. Roundness The wind is the most active agent shaping the particles and abrasion, especially through the impact of particle to particle contact. It usually causes the removal of corners and tends to round particles. The average percentages of roundness subclasses for upwind and downwind samples are similar (6.7%). The subrounded (34%), rounded (24%), and well-rounded (19%) particles are the most dominant within the studies samples. On the other hand, there were appreciable numbers of angular and subangular particles within both upwind (22%) and downwind (20%) aeolian sediments (Table 3). This may give evidence to the effect of local sources and a lesser effect of regional sources. BET surface area onmental history longer than other quartz particles. It is worth mentioning that the pits, either V-shaped or crescentic and rounded, cover most of the particles and other microfeatures, indicating they are younger than other surface microfeatures. Chemical microfeatures Irregular solution and silica precipitation represent the only abundant chemical microfeature within the studied samples. Other microfeatures such as silica plastering, deep surface solution, oriented V-shaped pits, disintegration by solution, and large-scale decomposition, respectively, occur to a limited extent. Chemical surface features are present with sporadic distribution and vary in extent from one particle to another. Deep grooves are present, sometimes deeply etched, and are commonly overlapped by mechanical features such as conchoidal fractures and deep triangular pits (Fig. 6e). A frosted appearance with large depressions is common on the The surface area values of all the Kuwait aeolian and the Al-Dibdibba Formation samples are presented in Fig. 7. The surface area values range from 1.479 to 4.505 m2 g−1, but the majority of the samples range between 2.5 and 3 m2 g−1. The average surface area for all aeolian sediments is 3.03 m2 g−1. The Al-Dibdibba Formation shows a similar average surface area of 3.1 m2 g−1. Upwind samples surface areas The upwind samples show little difference compared with the downwind samples. The general trend for upwind samples shows slight decrease downwind. The average surface area for the first, second, and third groups of samples is 3.485, 2.750, and 2.446 m2 g−1, respectively. The upwind samples have a larger range and a higher standard deviation (0.69) compared to the downwind samples. Arab J Geosci (2013) 6:519–527 Fig. 6 Scanning electron micrographs of representative quartz sand particles. a Smoothed well-rounded quartz particle with mechanical Vshaped and rounded and crescentic pits, and dish-shaped depressions. b Quartz particle with deep chemical pitting. c Angular particle with several mature conchoidal fractures. d Particle with medium outline 525 relief containing varieties of microfeatures including meandering ridges (1), upturned plates (2), capping layers (3), conchoidal fractures (4), and adhering particles (5). e Deep grooves, cracks, and deep chemically etched V-forms. f Generalized etching pattern, disintegration by solution and V-shaped sutures (1) and weathered feldspar-inclusion (2) 526 Arab J Geosci (2013) 6:519–527 Table 3 Number of particles and percentages for each roundness subclass Roundness class Angular Subangular Subrounded Rounded Well-rounded Subclass Aeolian samples (366) Upwind (166) Downwind (200) No. of particles % No. of particles % No. of particles % High Medium Low High Medium 1 35 2 8 21 0.3 9.6 0.5 2.2 5.7 0 16 1 5 9 0 9.6 0.6 3 5.4 1 19 1 3 12 0.5 9.5 0.5 1.5 6.0 Low Low Medium High Low Medium High Low Medium High 9 12 70 42 26 47 25 29 19 20 366 24 2.5 3.3 19.1 11.5 7.1 12.8 6.8 7.9 5.2 5.5 100 6.7 5 6 38 18 12 21 11 10 7 7 166 11 3.0 3.6 22.9 10.8 7.2 12.7 6.6 6.0 4.2 4.2 100 6.7 4 6 32 24 14 26 14 19 12 13 200 13 2.0 3.0 16.0 12.0 7.0 13.0 7.0 9.5 6.0 6.5 100 6.7 Total Average Total number of particles is shown in brackets Downwind samples surface areas Summary and conclusions The average surface area of the downwind samples is 3.124 m2 g−1 and slightly higher than upwind samples. But the values overlap at 1 standard deviation. The sample surface area ranged between 1.955 and 4.317 m2 g−1. There is considerable variation between one sample and another, but the variation is much less than the upwind samples. The samples are scattered without any significant trend. The scattering of samples is more evident toward the downwind side. The physical properties of particles within dominant aeolian deposits show unique characteristics. Variations within these properties are absent or limited. There is a close similarity in particle color between upwind and downwind samples within local scale. Also, a strong similarity in the four main particle shape parameters (area, equivalent diameter, elongation, and perimeter) is observed between upwind, downwind, and AlDibdibba Formation samples. The analysis of quartz particle in the SEM shows the influence of transportation on the Fig. 7 Variability of average surface area of medium sand size fraction from different aeolian deposits and the Al-Dibdibba Formation Arab J Geosci (2013) 6:519–527 microfeatures of individual particles. The aeolian environment provides the dominant fingerprint on the surface of the quartz particles, although the overall particle shape appears to have been modified only to a limited extent. Wind abrasion and impact between particles remove corners and produce upturned plates around fractures and cracks. As a result, the quartz particles located downwind in the southeast tend to be more rounded and smooth compared with those upwind in the northwest. It was observed that mechanical surface features on the surfaces of quartz particles occur mostly in the form of dishshaped depressions, V-shaped pits, upturned plates, rounded, and crescentic pits, respectively. This indicates the high influence of particle to particle contact when saltation takes place within the aeolian environment. The surface area variability between upwind and downwind areas was very small, indicating that the change in three-dimensional particle texture over a small distance is limited. The similarity in physical properties indicates a common origin for aeolian (upwind and downwind) and AlDibdibba Formation samples. It also indicates that these samples have experienced the same environmental conditions. Acknowledgments This work was funded by two foundations. These are Kuwait Foundation for the Advancement of Science (KFAS) for project (2008-1505-03) and the Kuwait Institute for Scientific Research (KISR) for (ECO77C). Thanks also to Mr. I. Ibrahim for helping in drafting some of the figures. References Al-Dousari AM, Pye K (2005) Mapping and monitoring of dunes in northwestern Kuwait. 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