The Neoproterozoic basement rocks of the Haggar Dungash area, Barramiya district, encompass ophiolitic assemblage of allochtonous blocks and clasts of serpentinite, metagabbro, metabasal and amphobolitest, which are tectonically embedded in highly sheared matrix of highly sheared ultramafic derivatives. This assemblage is separated from island arc volcanic/volcaniclastic rocks by oblique thrust and strike-slip faults, while discrete elongate bodies of gabbro-diorite and granitic intrusions occur along the axial planes of plunging anticlines and fault intersections.
Synthesis of the structural elements indicates three-fold deformational history (D1, D2 and D3), which accompanied with two main shortening events; one major during D2 followed by a local one during D3. The earlier (D1) is rare and preserved in the highly sheared ophiolitic derivatives and, sometimes, in the Island arc volcanics. D1 fabrics include WNW-ESE foliation (S1) and fold axes and WNW-ESE minor thrusts. Shortly, it was coeval with the initial stage of terrane accretion but their structural features are strongly superimposed by a later deformation (D2). D2 fabrics include abundant WNW-ESE to ~ E-W oblique thrust and WNW- to W- plunging folds. Transpression regime was recognized on the WNW-ESE strike-slip faults and related to the partitioning of deformation between sinistral shear and thrust component. D3 Structures are the result of movement along Idfu-Marsa Alam dextral shear activated northward in the present area and reflected by the influence of F3 overturned fold and parallel ENE-WSW dextral strike-slip fault.
Structural modeling shed light on the change from early ENE-WSW to E-W compressional regime into a late NNW-SSE shortening related to 1 rotation from ENE or ~E to NNW. The tight and overturned morphology of D3 folds, together with the oblique movement on the WNW-ESE to ~E-W transpressive faults indicate a rather intense, non-coaxial or deformation via simple shear during the Pan-African orogeny. This regime is followed during D3 by less intense, non-coaxial ENE-WSW dextral shear.
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