Late Proterozoic tectonic terranes in the Arabian-Nubian Shield and their characteristic mineralization

摘要: An extensive terrane of continental gneisses and supracrustal metasediments extends from the Nile valley westwards between southern Egypt northern Kenya, also occurs in Ethiopia, Somalia parts easternmost Arabian Shield. Mica–beryl pegmatites associated kyanite are characteristically developed. The gneiss terranes were regionally affected by metamorphic overprinting remobilization thus masking their true age which is considered to be Middle Proterozoic or older on basis isotopic petrological evidence. Between volcanosedimentary–ophiolite sequences intrusive synorogenic calc-alkaline batholiths, post-tectonic anorogenic alkaline plutons occur an area 700 km width over 2700 long Sinai Kenya. Within this region oceanic crust seven ophiolite- shear-bounded recognized developed around 900 600 Ma, through closure island-arc volcanism sedimentation, oldest being southeast. Hydrothermal gold mineralization widespread but restricted terranes, volcanogenic base metal sulphide deposits lithologically–tectonically controlled preferentially located parallel certain ophiolite margined plate boundaries.