The Lithostructural setting of Tullu Dimtu Neoproterozoic metamorphic rocks of western Ethiopia were comprised tectonically interleaved components of East African Orogen (EAO). Systematic field observations combined with petrographic investigations comprises variably polydeformed and metamorphosed metavolcano-sedimentary, mafic-ultramafics, and granitoids units. The interconnections and cross-cutting relationships of slightly foliated gneissosity, fold axial surfaces, ductile shear zones, and strike-slip faults manifests four phases of deformations in the area. The weekly foliated lenses of ferromagnesian rocks due to extensive shortening (D1) as a relict with in eastern high grade rocks were north northeast-trending and dipping subhorizontal to east. The variably dipping of axial surfaces and crenulation cleavage, and easterly plunging mineral stretching manifests the crustal thickening due to thrusting and folding (D2) causes for the migmatization of biotite-hornblende gneiss.

Keywords : Mafic-Ultramafic; Migmatitic Gneiss; Escape Tectonics; Shear Zone; Tullu Dimtu.