الفهرس 
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Abstract
The ophiolite sequences, which have been obducted onto continental crust, are typically underlain by a mélange (tectonic mixture). Large-scale mélanges formed at convergent plate margins generally consist of altered oceanic crustal material and blocks of continental slope sediments in a sheared mudstone matrix. The mixing mechanisms in such settings may include tectonic shearing forces, ductile flow of a water-charged or deformable matrix (such as serpentinite).In Egypt, ophiolitic rocks and ophiolitic mélange are widely distributed in the central and southern parts of the Eastern Desert. In the Central Eastern Desert (CED), ophiolites occur as clusters in the northern and southern segments (Farahat, 2010). These ophiolitic rocks are part of the Neoproterozoic oceanic lithosphere, which have been dated at about 880 -750 Ma (Stern, 1994). The study of these rocks may give valuable information for our understanding of the geologic history and tectonic evolution of the Arabian Nubian Shield (ANS) orogenic belt. The area under investigation (Wadi Um Laseifa area) represents part of the exposed Neoproterozoic basement complex in the southern part of the CED (Fig. 1.1).