Analysis of the microstructures and deformation mechanisms in the Eastern part of the Dehsheikh ultramafic-mafic complex, Esfandagheh region, South of Kerman province

Dehsheikh ultramafic-mafic complex is located in the Esfandagheh ophiolitic mélanges belt of Kerman province. The Dehsheikh complex comprises harzburgite, lherzolite, dunite, chromitite, pyroxenite and layered gabbros. The presence of abundant chromite ore deposits has made this complex important. The complex constitutes part of the Neotethys oceanic lithosphere deformed during upwelling from the upper mantle and later emplacement in the upper levels of the Sanandaj-Sirjan continental crust. Microstructural analysis of this complex reveals three deformation mechanisms including intracrystal plasticity, diffusive mass transfer and cataclasis. The microstructures of deformation twins, wavy extinctions, kink bands, exsolution lamellas, dynamic recrystallizations, microboudins, pull-apart microfractures, mineral stretching and elongation, mineral lineations and shear band cleavages formed due to the intracrystal plasticity deformation mechanism. The diffusive mass transfer deformation mechanism was associated with development of indenting, truncating and inter-penetrating grain contacts and micro-veins. The cataclasis deformation mechanism was accommodated by development of micro-fractures and micro-faults. This microstructural study also manifested different generations of olivines, pyroxenes and spinels under upper mantle to crustal conditions.