Abou EI-Hag G.T.!. and A.E. Hassanein( 2010). PEDOLOGICAL AND MINERALOGICAL ASPECTS AS CRITERIA OF SOIL GENESIS AND FOR1'fATION CHEMICAL AND MINERALOGICAL CHARACTERISTICS OF SOME SHALE DEPOSITS IN EGYPT AS AFFECTED BY DEPOSITIONAL ENVIRONMENTSEgypt . j .of appl.sci .,25 . (6A)
Abstract: Ten shale samples collected from different depositional environments ( marine, non-marine and brackish water) , in the northern parts of both eastern and western desert, Egypt. Some physical, chemical and mineralogical characteristics of these samples have been determined to infer the factors regulating their distribution in such environments . The mineralogical analyses on the separated clay fraction using XRD , revealed the presence of interstratified minerals, dominance of smectite relative to kaolinite and illite. Quartz, feldspars and calcite represent the non- clay minerals encountered . Smectite members are montmorillonite and vermiculite , the abundance of smectite relative to kaolinite was int1uenced by crystallization from ion-enriched hydrolytic solutions in badly-drained alkaline soils as well as marine neoformation , while the origin of kaolinite was attributed by the extensive chemical weathering and leaching of the exposed granite-metamorphic basement areas , illite is found in all shale sful1ples but it was enriched in the marine shale. Chemical data reflected the concentration of mobile elements ( Fe , Ca , Na , K and Mg ) . Major elements concentrations reflect the dominant mineralogical composition and the weathering history of the source area. Values of the Chemical Index of Alteration (CIA) [Ah03 / (Ah03+CaO + K20+ Na20) x 100] , indicated the moderate or limit degree of weathering of the source rock under the enviroI1..ment conditions. The statistical data clarify that, a positive sig..nificant correlations were found between the chemical characteristics of the studied shale samples and its mineralogical compositions in the different depositional environments. Mechanical analysis are also included in this study
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