Stratigraphy, Geochemical and Mineralogical Characterization of Lower Miocene Smectitic Clay Deposits, Case: South El-Hammam, Egypt.

Document Type : Original Article

Authors

1 Geology department, Faculty of science, Cairo University, Giza, Egypt

2 Geological Sciences, inorganic division and mineral resources, National Research Centre, Cairo, Egypt

3 Department of Geology, Faculty of Science, Cairo University, Giza, Egypt

Abstract

This work discusses the physical, geochemical and mineralogical characterization of some bentonite resources in South El-Hammam area which are hosted in thick sandstone sequences belonging to the Lower Miocene Moghra Formation. Bentonite samples were characterized by microscopic, SEM, XRD and ICP-MS analyses. Bentonite resources in this study consist of montmorillonite as the main clay mineral of all the analyzed samples. Kaolinite also occurs as minor clay constituents. The identified non-clay minerals include; quartz, albite and calcite. The highest grade of the studied bentonite, contains Si/Al molecular ratio of 2, suggesting absence of detrital quartz. In contrary, the lowest grade of bentonite with alumina content of 15.06%, display Si/Al molecular ratio of 4.34, where free silica dominates over bentonite. The REE content of the Lower Miocene bentonite study area is strongly imparted by LREE signature. The very high CIA index (74.85 and 91.25) suggesting intense chemical weathering of source rock, which is supported by the presence of Ce abnormality, indicating that they were deposited under pluvial conditions.

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