Author(s): Mostafa M. Soliman
Article publication date: 1984-09-01
Vol. 2 No. 2 (yearly), pp. 113-123.
228
Keywords
Egypt, plutonic rocks, oxidation
Abstract
The oxidation ratio ((2Fe2O3 x100)/ (2Fe2O3 + FeO)) of the granitic rocks of the Aswan batholith range from 8 to 90 and increase with the increase of differentiation index from older to younger rocks. The batholith was formed by crystallization of magma under buffered conditions with respect to oxygen. The buffer was magnetite, lower levels of oxygen pressure were maintained during the formation of the earlier phases of the batholith, and higher pressures of oxygen prevailed during the generation of the later phases. The earlier phases were probably produced by melting pf parental mantle-derived anhydrous material and crustal rocks. The later phases were probably formed entirely by melting crustal materials of sialic composition. The initial Sr87/Sr86 ratios of the earlier phases range from 0.7052 to 0.7352 and may support this view.