Origin and evolution of Neoproterozoic metaophiolitic mantle rocks from the eastern Desert of Egypt: Implications for tectonic and metamorphic events in the Arabian-Nubian Shield

The mantle rocks from Kadaboura and Madara areas represent sections of dismembered ophiolitic complexes developed during the Neoproterozoic in Eastern Desert Egypt, which is located northwestern corner Arabian–Nubian Shield. comprise serpentinites serpentinized dunites, whereas those consist pyroxenites.Despite serpentinization studied rocks, few relicts primary chromite, olivine pyroxene are preserved. Chromite partly altered having unaltered Al-rich chromite cores surrounded by Fe-rich Cr-rich magnetite rims. show compositions equilibrated at temperatures mostly below ~500-600°C, a temperature comparable to that estimated for greenschist up lower amphibolite facies rocks. high Cr# [100×Cr/(Cr+Al)= 47-76] Mg-rich nature (Fo91–94) indicate were produced highly depleted experienced degrees melt extraction (mostly ~30-40%). This range resembles supra-subduction zone peridotites, but higher than abyssal passive margin peridotites. Furthermore, clinopyroxene Mariana forearc Bulk-rock geochemistry also reflects derivation an extremely refractory source. Modelling rare-earth elements suggests possibly formed interaction their harzburgitic precursors with subduction-related melts/fluids evolution fore-arc basin zone.The proposed geodynamic model oceanic lithosphere generated seafloor spreading Mozambique Ocean was emplaced upper plate intra-oceanic subduction zone, formely Arabian-Nubian Shield mature phases hydrous melting, extreme depletion enrichment.