Stream Sediments Geochemical Exploration in the Northwestern Part of Wadi Allaqi Area, South Eastern Desert, Egypt |
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Authors: | Ahmed M El-Makky Kadry N Sediek |
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Institution: | (1) Biological and Geological Sciences Department, Faculty of Education, Alexandria University, Soter, Alexandria, Egypt;(2) Geology Department, Faculty of Science, Alexandria University, Alexandria, Egypt |
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Abstract: | Geochemical stream sediments survey was conducted in the northwestern part of Wadi Allaqi area, Eastern Desert, Egypt. The
area comprises Precambrian metasediments, intermediate metavolcanics, gabbro, and serpentinites, with intrusive masses of
granites and quartz-porphyry and invaded by several quartz veins. The −1.0-mm size fraction is analyzed for As, Cu, S, Mo,
Pb, Zn, Co, Ni, Rb, Ba, Sr, Nb, V, U, Th, Cr, Zr, La, Ce, Nd, and Y. The geochemical survey is supported by heavy minerals
study in the −0.125 + 0.0625-mm fraction. The geochemical data were statistically investigated using Q-mode cluster and R-mode
factor analyses as well as the enrichment factor. Factors 1 (Zr, Nb, Nd, La, and Y), 2 (V, Sr, and Zn), and 4 (Ba and Rb)
are mainly controlled by the lithological characters of the rocks hosting Au-sulfide mineralizations and their accompanied
hydrothermal alteration zones. In the mineralization Factor 3 (Cu, S, As, Ce, and Mo), arsenic, Cu, S, and Mo are direct indicators,
while Ce is indirect one for the Au-sulfide mineralizations. The Cu–S–As–Mo association with Pb and Zn anomalies in the stream
sediments draining the quartz-porphyry point to its porphyry copper mineralization. Cobalt and Ni (Factor 5) are pathfinders
for the Fe- and Cu-sulfides, whereas Zn and Pb of Factor 8 are additional pathfinders for the Au-sulfide mineralizations.
The southern stream sediments having high U/Th ratios with U–Mo association and draining granites traversed by pegmatites,
as well as the stream sediments draining Um Garayat area and the quartz-porphyry stock with high abundance of monazite, zircon,
epidote, sphene, and ilmenite, could signify sources of U and Th (Factor 7). Two watershed areas have distinct enrichment
factors for arsenic suggesting unexplored extensions of Au-sulfide mineralization linked to the Allaqi shear-zone. The enrichment
of the mineralization Factor 3 in the drainage system is mainly controlled by the prevailed mechanical dispersion for the
hosting heavy minerals in such arid region with minor role of hydromorphic dispersion. The chemistry and mineralogy of the
stream sediments are evidently allied to the drained bedrocks and their hosted mineralizations that signify a promising area
for detailed exploration. |
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