Soil Genesis and Uniformity of Wadi Al-Queh, Al-Quseir, Red Sea Coast, Egypt

Abstract

Red Sea coastal zone within the "Golden Triangle" national project is brought out as promising agrarian expansion. Wadi Al-Queh is one of the drainage basins located east of Red Sea Mountains with buoyancy water and soil resources.Current study aimed at investigating soils of wadi Al-Queh with respect to their genesis and degree of homogeneity based on the mineralogical analysis. Four landforms were recognized running east to west namely; bajada plain, wadi terraces, mid-stream wadi course and piedmont plain. Twenty nine soil samples were selected representing eight georeferenced profiles to embody all variations in the different landforms. To recognize the prevailing depositional environmental conditions, samples were subjected to granulometric analysis for the sand fraction. Heavy and light minerals of fine sand fraction were estimated. The uniformity ratios among resistance minerals of zircon, rutile, and tourmaline were calculated. Weathering ratios (Wr1, Wr2, and Wr3) between the non-resistance and resistance minerals were used as criteria for investigating parent materials uniformity and consequently the degree of soil development. Obtained results revealed the dominance of quartz with 89.15-98.85% of the total light minerals. Opaque minerals are composed essentially by iron oxides in the range 37.75-71.25% of the total heavy minerals. Frequencies of transparent minerals indicate the contribution of igneous, metamorphic and sedimentary sources in soil derivation at whole landforms. They were mostly derived from Nubian sandstone, limestone, conglomerate, breccia, granite, basalt, and schist during Tertiary to Recent ages. Obvious heterogeneous distribution of calculated weathering and uniformity ratios with depth depicted that most of the studied soils were poorly sorted, poorly developed and mostly composed of more than one parent material under multi-depositional environments conditions with non-uniform in nature. Water as the major erosional agent contributes in rifting the wadi paths between mountainous blocks towards east direction. Weathered materials from igneous, sedimentary and metamorphic sources were deposited to form a great outwash plain in which the soils under consideration were stratified. In conclusion, it is quite clear that soils of wadi Al-Queh represented an apparent discontinuity or a type of irregular interstratifications due to geogenetic weathering, mostly related to a multi-origin and/or multi depositional regime.