Abstract
The tectonics and impact of the Pan-African orogeny on the Hong Hills area of North Eastern Nigeria has been unraveled. This work basically used structural identification and tectonic inference to decipher the deformation episodes in this region. The results show that this area was subjected to multiple episodes of deformation and there were evidence of reworking of older structures by younger ones. Foliation, folds and dykes/vein data suggests that the metamorphic rocks in this area experienced a predominant E - W compression during the Pan - African Orogeny. Structural evidence and the presence of dominant ductile shear zones also confirm that the deformation in this region is predominantly ductile. The relatively younger granite intrusions show structural trends which are consistent with the closing periods of the Pan-African Orogeny. Evidences show the emplacement of these plutons followed regional structural direction defined by major fold trends and rock foliation. Salient isolated features suggest the occurrence of pre Pan-African orogenic structures but there aren’t enough data or evidences to buttress this claim. From this work, we can safely say that the Hong Hills region is a complex Pan-African zone with two major episodes of deformation. Key words: Basement complex, geological structures, pan-African deformation, pluton emplacement.  
Highlights
The Hong Hills are part of the Pre-Cambrian basement complex in North Eastern Nigeria
Information from the geology and structures of the Hong Hills, an area lying in the south central part of Hawal Massif have given us a fair idea of the stresses that acted during the Pan – African orogeny
(i) There was dominant E – W compression: evidence from the preferred stretching of minerals in the N – S direction and the foliations and fold axes preferred the N - S direction. (ii) The deformation was predominantly ductile: evidence from the conspicuous absence of fractures which have probably been healed by intruding dykes and mineral veins
Summary
The Hong Hills are part of the Pre-Cambrian basement complex in North Eastern Nigeria. This complex is a section of the 3000 km long Trans-Saharan belt which formed in the Neoproterozoic (between 750 and 500 Ma) by a continental collision between the converging West African, Congo and East Saharan blocks (Ferre et al, 2002). The Pan-African mobile belt, within which the Hong Hills lies, contains high-grade metamorphic assemblages which expose middle to lower crustal rocks (Kalsbeek et al 2012, Ekwueme and Kroner 1997). The exact origin, environment of formation, tectonics and structural evolution of these Pre-Cambrian rocks are quite difficult to reconstruct and this is why we use observed structures in this region to try and present the deformation episodes that took place in this region.
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