Sand mineralogy, origin, uniformity and weathering ratio of some soils in Elgalaba plain, Aswan, Egypt

Document Type : Research article

Authors

Department of Soils and Water, Faculty of Agriculture, Al-Azhar University, Assiut 71524, Egypt

Abstract

The main aims of this study are to study the mineralogical composition of very fine sand fraction and estimating the origin, uniformity and weathering degree of the soil material in the soils of the investigated area. A total of forty-three soil samples were collected from twelve soil profiles according to the pedomorphic variations. The investigated soil profiles show a coarse texture of sand and loamy sand, as well as moderately coarse texture of sandy loam. The light fraction was the fundamental constituent of the very fine sand fraction of the studied soils. Ferthermore, all soil samples of the studied area were exhibits relatively low contents of heavy fraction in the very fine sand fraction and their index figures. The light minerals were mainly composed of quartz followed by feldspars, with irregular distribution of these minerals with depth. Opaques minerals were the most predominant constituent in all samples. They range from 35.78 to 91.25 % of the heavy fraction, without any systematic vertical distribution. Whereas the non-opaques were the less abundant in the heavy minerals of most of the studied soil samples and include zircon, tourmaline, pyroxenes (augite and enstatite), garnet, epidot, rutile, biotite, amphiboles (hornblende) and staurolite. The assemblages and frequencies of these light and heavy minerals of the studied soil samples suggest that the origin of these soils derived from different provenances. Regarding, uniformity of the studied profiles, the results showed these soils were formed from materials of heterogeneity nature and could be considered young from the pedologic point of view. These results also showed that weathering ratios in the surface layer were lower than in the subsurface layer of the majority of soil profiles reflecting a slight effect of weathering in the surface layer and pronounced amounts of the resistance minerals in these sediments.

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