M. Blasy, S.A. Azzaz, Kh. ALRashidi
Abstract: The significance of Nb, Zr, Y, Ti, and REE and the use of their ratios in the Tertiary and Early Cretaceous basalts of Egypt have not been previously noted. The study deals with three basaltic occurrences around Gulf of Suez representing two episodes.Tertiary basalt of Abu Zenima and Ehamer areas show within plate continental /oceanic transition setting and tholeiitic. Early Cretaceous basalt of Abu Darag area are alkaline and within plate continental. In terms of high field strength elements and REE abundances and their ratios, some geochemical constraints has been revealed 1- The Y/Nb, Zr/Y, Zr/Nb and LREE/HREE of Tertiary basalts are more comparable but differ than the Early Cretaceous one suggesting two mantle sources, 2-K2O, Na2O, Nb, Zr, La/Sm and LREE/HREE of the Early Cretaceous basalt are higher than those of Tertiary one suggesting enriched mantle source or small degree of partial melting at greeter depth, 3- The chemical weathering has increased LOI, MgO and K2O and decreased CaO from the marginal part of the Abu Darag basaltic dyke, upper part of Abu Zenima flow and Ehamer dyke, 4- The Early Cretaceous basalt shows a greeter crustal contamination than Tertiary one as indicated from, higher K2O/P2O5, Rb and Th and Lower Zr/Nb, and TiO2/ P2O5 than Tertiary one.
Keywords: basalt, Tertiary, Cretaceous, high field strength elements, REE