Abstract

Recent tectonic models have resulted in conflicting descriptions of how the late Precambrian sutures of the Arabian-Nubian shield extend into northeast Africa. The Hamisana shear zone in northeastern Sudan is critical to this discussion because it truncates and disrupts two sutures, the Allagi-Heiani and the Onib-Sol Harried. Analysis of field structural data, thematic mapper imagery, and Rb-Sr and U-Pb geochronology suggests that the Allagi-Heiani suture is the western extension of the Onib-Sol Harried suture and that both make up the exposed parts of a far-traveled, polydeformed ophiolitic nappe complex. Subsequent deformation localized in the Hamisana shear zone disrupted this nappe and displaced the suture between 660 and 550 Ma during regional deformation associated with the Najd fault system. These results indicate that at least one suture extends westward into the interior of northern Africa.

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