A Metamorphic Core Complex Model for the Host of Uranium Mineralization in the Khoshoumi Mountain, Central Iran

Abstract

A metamorphic core complex model is proposed for Khoshoumi Mountain uranium mineralization located in the Bafq-Saghand metallogenic zone of central Iran. Uranium mineralization occurred in the Chapedoni metamorphic complex. Detailed structural analysis of the complex leads to the interpretation that the mineralization is spatially concentrated in a low angle shear zone of mylonitized migmatite, the lower ductile part of the Chapedoni metamorphic complex. The shear zone that has top to the NE sense of shear in the northeastern and southeastern parts of the mountain and top to the WNW sense of shear in the southwestern part is a detachment zone to the Chapedoni Metamorphic Core Complex (CMCC). The Eocene granite is the plutonic core to the CMCC. The shear zone is cut by several NE-trending left-lateral strike-slip faults. This later faulting is interpreted to account for the significant enrichment of uranium in the southern part of the mountain. The bimodal distribution of radiometric data gathered from exploratory drill holes in this part of the mountain constrains this interpretation. That is, the lower value is from the shear zone across the area but the higher value is from the places that the shear zone is cut by the transverse faults.