GEOMORPHOLOGY AND GENESIS OF SOME SOILS EAST AND SOUTH El QATTARA DEPRESSION | ||||
| Egyptian Journal of Agricultural Research | ||||
| Article 1, Volume 90, Issue 3, September 2012, Page 967-989 PDF (898.27 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ejar.2012.161364 | ||||
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| Authors | ||||
| MOHAMED M. ISMAIL; MPHAMED A. AZZAM; MAMDOUH K. ABDEL GHAFFAR | ||||
| Soils, Water and Environment Research Institute, Agricultural Research Center, Giza, Egypt | ||||
| Abstract | ||||
| The aim of the current work is to study the geomorphology and genesis of some soils east and south El Qattara Depression at the north of the Western Desert, Egypt. The study area is located between latitudes 29° 41′ and 30° 30′ N and longitudes 27° 39′ and 28° 43′ E. The study area can be divided into five geomorphic units namely: Plateau, Pediments, El Qattara Depression, Alluvial plain (western and eastern) and Sand dunes. The soils of these units are mostly sand texture except El Qattara Depression unit which has a sandy loam to clay loam texture. The graphic mean size index is mostly ranging from fine to coarse sand size. The sorting index ranging from moderately well sorted to poorly sorted indicating aeolian and aqueous media of transportation and deposition except the sand dunes unit where the graphic mean size index is fine sand and the sorting index is moderately well sorted indicating aeolian media of transportation and deposition. The sand fraction consists of light and heavy minerals. The light minerals are the main constituent of sand fraction and consists mainly of quartz (≥ 90 %) followed by feldspars (plagioclase and orthoclase) in addition to muscovite and calcite minerals. The heavy minerals consist of opaques and non-opaques. Opaque minerals are the major heavy fraction constituent in all the examined soils and composed essentially of iron oxide minerals. The complementary non-opaque minerals consist of: (a) Sedimentary origin minerals, which also named ultrastable or index minerals, are mostly dominating the non-opaque minerals. (b) Igneous origin minerals or unstable minerals are the second abundance minerals in the study area. (c) Metamorphic origin minerals or metastable (index) minerals are detected in considerable portions in the study soils. The source rocks of sand in the study area are mixture of sedimentary, igneous and metamorphic rocks. However, the sedimentary rocks are the first source of sands in western alluvial plain sub unit. The vertical distribution of amphiboles, pyroxenes and index minerals change irregularly depth wise indicating that the study soils are recent, poorly developed and immature from the pedogenic point of view. The soils of western alluvial plain sub unit are partly affected by Nile sediments than other study units where the Nile sediments during flood periods deposited mostly in the near land south of El Qattara Depression. | ||||
| Keywords | ||||
| Geomorphology; Metamorphic origin; Sand Mineralogy | ||||
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