Abstrart: Whole-rock Rb-Sr studies on six suites of highly metamorphosed basement rocks from southern Egypt and northern Sudan, west of the River Nile, yield Pan-African ages (562-918 Ma): these ages are interpreted as reset. Orthogneisses give Nd model ages of 1600 to 2600 Ma for their calc-alkaline plutonic precursors. A gneiss derived from sedimentary precursors gave a mean crustal residence age of 2200 Ma. A series of I-type, late-tectonic, granitoids were intruded during a period of uplift, erosion, and wrench faulting at 560-620 Ma. Geochemical characteristics and Nd model ages (1200-1700 Ma) indicate that these rocks were derived from a mixed source of juvenile Pan-African mantle material and older continental crust of mainly early/middle Proterozoic age. Negative ENd, values for granitoid samples (-18.9 to -5.3) show that the Pan-African episode in NE Africa, west of the Nile, involved considerable reworking of pre-existing crust.It is now generally accepted that the development of the Arabian-Nubian shield was one of microplate accretion due to subduction-related processes and collisional tectonics during the Pan-African event (950-500Ma), although the details are still being debated (Kroner

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We have measured the density of Pd40Ni40−xCuxP20 (x=0–40) alloys in the amorphous and crystalline states. For x>30, the alloys are denser in the amorphous than in the crystalline states, which is contrary to the behavior of all known metallic glasses. For Pd40Ni40−xCuxP20 and all other bulk metallic glasses where density data are available in both the amorphous and crystalline states, we find a correlation between the stability of the supercooled liquids and the difference between the molar volumes of the glassy and crystalline phases. The supercooled liquid region is largest for those alloys that show no change in molar volume upon crystallization.

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