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In the central-eastern Bayuda Desert (Sudan), a border area between the Saharan Metacraton and juvenile Pan-African crust of the Nubian Shield, the Rahaba-Absol and the Abu Harik-Kurmut Terranes were amalgamated along suture and shear zones. U-Pb zircon ages by laser-ablation dating of metamorphosed granitoid rocks reveals ages interpreted as magmatic and metamorphic activities throughout the Neoproterozoic. The meta-granitoids are calc-alkaline porphyroblastic varieties of biotite metagranite (969 +/- 5 Ma), quartzfeldspathic metagranite (914 +/- 6 Ma), biotite-muscovite metagranite (912 +/- 4 Ma) and coarse-grained meta-monzodiorite (909 +/- 9 Ma, 818 +/- 19 Ma, 669 +/- 13 Ma) associated with the Rahaba-Absol Terrane, and medium-grained metagranites (813 +/- 4 Ma, 808 +/- 5 Ma, 799 +/- 16 Ma), a metaquartz-monzonite (810 +/- 10 Ma), biotite metagranites (794 +/- 15 Ma, 783 +/- 13 Ma, 700 +/- 7 Ma), alkali metagranite (645 +/- 5 Ma), and porphyritic meta-quartz-monzonite (630 +/- 4 Ma) associated with the Abu Harik-Kurmut Terranes. Th/U ratios of the zircon were used to distinguish between intrusion and metamorphic ages.

The Neoproterozoic ages are interpreted as geodynamic pulses: a pre-Pan-African event 1000-900 Ma characterized by metamorphism and magmatism ending with the known Bayudian Event (920-900 Ma) in the Rahaba-Absol Terrane; a cycle between 850 and 775 Ma of subduction-related magmatism and metamorphism with a peak around 825-800 Ma; the final collision of the Rahaba-Absol and Abu Harik-Kurmut Terranes began before 714 Ma and ended probably before 645-630 Ma, documented by discordant E-W trending alkali metagranites and NE trending porphyritic meta-quartz-monzonite respectively. Theses ages of discordant intrusions constrain the post-collisional horizontal movement along the southern Keraf Shear Zone between 630 and similar to 590 Ma. The existence of inherited zircon grains in some samples of Pan-African age indicated sedimentary activity contemporaneous with the island-arc magmatism and metamorphism. This was probably a period of extensive erosion of the earlier island arc material and later stacked crustal material after terminal collisional between the Abu Harik-Kurmut arc and the Rahaba-Absol continental terrane. Pb isotope data (feldspar, whole rock) and Sr isotopes corroborate the division into two terranes, the Rahaba-Absol Terrane as an old cratonic part of the Saharan Metacraton, and the Abu Harik-Kurmut Terrane as juvenile island-arc additions during the Pan-African. (C) 2013 Elsevier B.V. All rights reserved.