The Neoproterozoic Keraf Suture in NE Sudan: Sinistral transpression along the eastern margin of West Gondwana

Abstract

The Keraf Suture, formed during the Neoproterozoic consolidation of Gondwana, is a ∼500 km long, ∼50 km wide, N-trending suture between the Neoproterozoic Arabian-Nubian Shield in the east and the older Nile Craton to the west. The Keraf Suture is superimposed on E- and NE-trending structures on both sides. The northern part of the suture is dominated by N-trending, upright folds, whereas the southern part is characterized by N- and NNW-trending, sinistral, strike-slip faults. A major antiform defines a structural divide between the northern and southern parts of the suture. 40Ar/39Ar ages on biotite and hornblendes separated from a deformed granitic body indicate that the sinistral movement along the N- and NNW-trending faults took place at ∼580 Ma. The difference in structural styles along strike is due to formation of the Keraf Suture by sinistral transpression, which accompanied early NW-SE oblique collision between East and West Gondwana at ∼650-600 Ma and terminal collision at ∼580 Ma.