Geochemistry and tectonic significance of polymetamorphosed amphibolites in the Gebel Sibai window, central Eastern Desert, Egypt - Khudeir, Ali Abdelkader Abdalla; Ǧabī, Samīr al-; Greiling, Reinhard O.; Ṣābir, Ğamāl Muḥammad Kamāl-ad-Dīn (Proceedings of the First International Conference on Geology of the Arab World ; 1, 1992)