GABAL ABU HAMR PLUTON: AN EXAMPLE OF A-TYPE ANOROGENIC PERALKALINE GRANITES IN EGYPT

Gabal Abu Hamr pluton is an elongated peralkaline granitic mass emplaced along the ENE-WSW
Qena-Safaga shear zone as one of the anorogenic peralkaline granites represented in the Eastern Desert of
Egypt. The rock is hypersolvus, composed of perthite, quartz and both alkali amphibole (arfvedsonite) and
pyroxene (aegerine). It is enriched in Si, Na, K, Ba, Y, Ga and LREE and depleted in Al, Mg, Ca, Mn, Zr
and HREE. The rocks exhibit mineralogical and chemical traits typical of within-plate A-type granites,
which, due to the ascending of hydrothermal solutions along the ENE-WSW strike-slip fault, dividing the
pluton, suffered metasomatic processes causing the leaching of Zr, U and HREE and their escape into the
fluids and transported through the structure systems to be concentrated along the tectonic contact between
the granite and the adjacent metavolcanics. This pluton may represent the northern extension of both G.
Abu Kharif and G. El Dob being emplaced along the same E-NE shear zone trend. The suggested age of
emplacement of G. Abu Hamr pluton is from 550 Ma to 450 Ma.