Eastward transport of the Monapo Klippe, Mozambique determined from field kinematics and computed tomography and implications for late tectonics in central Gondwana

We present a detailed kinematic study of the boundary between the Monapo Klippe and the underlying Nampula Block in northern Mozambique. The Monapo Klippe is an allochthonous klippe of granulite-facies metamorphic rocks with subsidiary granitic and mafic intrusive rocks. The klippe overlies the Nampula Block which is made up of ortho- and paragneisses that are lower metamorphic grade and considerably older than the rocks of the Monapo Klippe. The boundary between the klippe and the underlying Nampula Block is a distinct mylonitic shear zone of variable width. The mylonite composition varies with the local footwall lithology but the dominant composition is quartz-rich with minor feldspar augen and biotite. The mylonite is interpreted to have formed as an early broad ductile shear zone that evolved during multiple phases of shearing to a narrow high-strain, lower temperature mylonite horizon. Kinematic indicators observed in outcrop, thin section, and image slices from X-ray computed tomography of three-dimensional mylonitic fabrics record top-to-east motion. The granulite-facies Cabo Delgado Nappe Complex, which lies to the north of the Monapo Klippe, has been hypothesized as the root terrane for the klippe. The Cabo Delgado Nappe Complex records top to the north-west motion at around 630-610 Ma. However, granitic and pegmatitic rocks that intrude the Monapo Klippe, and which also cross-cut the mylonite fabric as well as being deformed by it, are considered to be part of the Cambrian Murrupula Suite dated at between 530 and 470 Ma. This suggests that the emplacement of the Monapo Klippe over the Nampula Block is part of a later extensional phase post 530 Ma associated with east-directed post-orogenic collapse following Gondwana assembly.