Petrological and Geochemical Characteristics of Wadi Sikait Lamprophyre Dykes, South Eastern Desert, Egypt: Implications for Petrogenesis and Crustal Contamination


  • Amira M. El Tohamy Nuclear Materials Authority, P.O. Box 530 El Maadi, Cairo, Egypt.
  • Mohamed S. Kamar Nuclear Materials Authority, P.O. Box 530 El Maadi, Cairo, Egypt
  • Ahmed M. Ismail Nuclear Materials Authority, P.O. Box 530 El Maadi, Cairo, Egypt.


Lamprophyre dyke, Gold, Base metals, REEs, Eastern Desert, Egypt


The lamprophyre dykes extruded in the psammitic gneisses, ophiolitic mélange, and monzogranites at Wadi Sikait provinces. Microscopic investigation of the lamprophyres indicates that they are mostly composed of spessartites and kersantite. The microscopic and ESEM investigations on the accessory minerals revealed the presence of monazite-allanite, yttrocolumbite, gold, cassiterite, wolframite, galena, and native nickel. Geochemically, the lamprophyres are basalt and basanite/tephrite in composition with calc-alkaline characters. They are enriched in TiO2, Fe2O3, MnO, CaO, Na2O, P2O5, V, Zn, Li, Nb, Ta, Th, Zr, and U however depleted in SiO2, Al2O3, MgO, K2O, Cr, Co as well as Ni relative to the corresponding rock types. The high LILE contents, Nb and Ta relative to Hf, depletion in HREEs, along with elevated Ba/Nb and Ba/La ratio illustrate an enriched mantle source. The enrichment of LREEs in the lamprophyre dykes indicates a low degree of partial melting. High Ba and U values implies the addition of Ba and U to the protolith via metasomatism or hydrothermal fluids in the source region. The peculiar M-W type tetrad effect confirms the effect of the water-rich phase and could be an indication of Au mineralization, as indicated by the presence of gold grains in the separated heavy fraction.