ON THE GEOCHEMISTRY OF AMPHIBOLITE ENCLAVES IN THE PAN-AFRICAN GNEISSES OF WADI FEIRAN, SW SINAI, EGYPT, AND THEIR RELATION TO ARC MAGMATISM

Abstract

Geochemistry of amphibolite enclaves from the Pan-African Wadi Feiran area, SW Sinai, is presented
with the aim to assess the petrogenetic characteristics of their protliths. These enclaves are concordantly
enclosed in biotite, hornblende and quartzofeldspathic gneisses and schists, that overlie partially
migmatized granitic gneisses. They occur as variably sized, massive to highly foliated and often strongly
stretched, lenses and boudins. The studied enclaves are of magmatic origin with precursors ranging from
calc-alkaline andesites to tholeiitic basalts. Rare enclaves of high-Mg appinitic monzogabbro and
monzodiorite are recorded in the biotite gneisses, indicating a primary magma that was generated along a
subduction zone. The geochemical characters of the studied enclaves indicate that during the Pan-African,
the Wadi Feiran area constituted a back-arc continental lithosphere environment that witnessed plumesubduction
interaction.

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