Petrology and geochemistry of ophiolitic ultramafic rocks and chromitites across the Eastern Desert of Egypt: Insights into the composition and nature of a Neoproterozoic mantle and implication for the evolution of SSZ system

•-The ultramafic masses are remnants of Neoproterozoic forearc depleted mantle and cumulates.•-The podiform chromitites record different evolution stages of Neoproterozoic SSZ system.•-The oxidation state of Neoproterozoic SSZ was not homogeneous.•-The Neoproterozoic forearc mantle rocks were cooled at low rate.