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Orientation of late Precambrian sutures in the Arabian-Nubian shield

Abstract:

Recent tectonic models have resulted in conflicting descriptions of how the late Precambrian sutures of the Arabian-Nubian shield extend into NE Africa. The Hamisana shear zone in NE Sudan is critical to this discussion because it truncates and disrupts 2 sutures, the Allaqi-Heiani and the Onib-Sol Hamed. Analysis of field structural data, thematic mapper imagery, and Rb/Sr and U/Pb geochronology suggests that the Allaqi-Heiani suture is the W extension of the Onib-Sol Hamed 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 550Ma during regional deformation associated with the Najd fault system. These results indicate that at least one suture extends W into the interior of N Africa. -Authors