ABSTRACT

Most models addressing the formation of the Arabian-Nubian shield (ANS) of northern Africa assume that juvenile Pan-African arc/ocean terranes assembled and accreted onto an old African craton to the west 600–950 m.y. ago. The precise location of the boundary between the ANS and the old African continent remains controversial. The nearest dated pre-Pan African rocks is in the Uweinat area some 600 km west of the exposed ANS. A seven-point Rb/Sr isochron age for granulites from this area yielded 2656 +/- 71 Ma. Using U-Pb (zircon) and Sm-Nd whole rock whole rock data for gneissic bedrock outliers from the Western Desert of Egypt this chapter documents the presence of pre-Pan-African crust in Gebel Kamil and Chephren quarries areas, some 400 km closer to the ANS. Four multigrain and two single zircon analyses from hornblende plagioclase gneiss define a wedge shaped array scattering away from Concordia.