Ore
deposits in Precambrian rocks of sedimentary affiliation in Egypt
Abd ElAziz A. Hussein
Geological Survey of Egypt, Cairo, Egypt. |
IRocks of sedimentary affiliation in the
Precambrian terrains of Egypt are known to host a substantial
proportion of ore and mineral deposits pertaining to that age.
Within the metasediments (paragneisses) of the south Western Desert, Algoma - type Band
Iron
Formation (BIF) was recently discovered, together with a quartz gneiss with bands or
streaks of
sulfides, locally altered into malachite. Of particular interest here, is the anomalous
concentrations of
gold contained in this formation. The graphite schist of the Eastern Desert occurs in
association with
the flysch-type geosynclinal metasediments of the Upper Proterozoic.
The beautifully colored bands of marble known from Wadi Allaqi and other areas in the
south Eastern
Desert represent the limestone beds that were present within the flysch sediments.
Similarly, the volcanogenic sediments (tuffs and siliceous sediments) of the same age are
known to host all the BIF occurrences of the Eastern Desert. The volcanogenic exhalative
massive sulfide deposits of the Um Samuiki - type were formed as sediments on the sea
floor in the form of lenses enclosed between volcaniclastic breccias (footwall) and
volcanogenic - sedimentary banded chert and tuffs (hanging wall).
Inspite of the fact that no mineral deposits have been located as yet within the molasse -
type sediments of the Hammamat Group of Late Proterozoic - Early Paleozoic age, yet it is
the conviction here that some paleoplacer gold deposits, similar in nature if not in
grade, to the Witwatersrand gold deposits of South Africa, are awaiting discovery within
the lower conglomeratic members of that group.
Moreover, the Hammamat Conglomerate (Breccia Verdi Antico) represents a unique ornamental
stone that is witnessing a come back in taste and value after it had been deserted since
Ancient Egyptian to Roman periods. The alluvial sediments in wadis draining the basement
outcrops contain at the favorable depositional sites, some placer deposits of gold
(Wadi Allaqi), cassiterite (Wadi Muelha) or columbite - tantallite - cassiterite (Abu
Dabbab). Precambrian rocks are the source of minerals of value in these deposits.
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