Clay
Minerals and Geochemistry of Late Quaternary Argillaceous Sediments
in Kom Ombo Area, Egypt
Hafez Sh. Abd ElWahab
Dept. Geology, Fac. Sciences, Ain Shams Univ., Cairo, Egypt |
Two Late Quaternary stratigraphic type
sections (Kalabsha East and Kalabsha West) at Kom Ombo are studied. The clay fractions (<2 m)
separated from sand and silt were examined by XRD and instrumental neutron activation. The
XRD data for 30 clay samples show that they consist of smectite, kaolinite and illite, in
order of decreasing abundance. The averaged clay-mineral composition as well as the K/S
and I/S ratios indicate one clay province during this time span. The trace element
concentrations are of considerable variations. The Kalabsha East clays are more enriched
in Cu, Ba, Br, Co, Cr, Cs, Hf, Ni, Rb, Sc and Th, while the Kalabsha West clays are more
enriched in Pb, Au, As, Ca. Fe, Na, Ta, U and Zn.
The systematic study of REE, their fractionation and distributional trends show
differences in their patterns between the clays of the two localities. This is in a
close agreement with the geostatistical data. Accordingly, from the geochemical point of
view, the clays of Kalabsha East section and those of Kalabsha West section can be
considered to be of two different geochemical clans.
The clay-mineral composition, beside the field observations, show that the Late
Pleistocene and Holocene clays in the two sections designate an arid to warm-subarid
climate during their deposition. Also, the wadi activities are found to have influenced
the input of sediments derived from the Red Sea mountains and fed into the Nile, together
with the load from the Central African Plateau, Atbara and the Blue Nile systems.
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