Relationship Between Structure and Lithology and their Control on Gold Mineralization in Okote Area, Southern Ethiopia
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Date
2013-06-06
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Addis Ababa University
Abstract
Okote gold field is found within Neoproterozoic greenstone terrains of southern Ethiopia. This greenstone belt trend in North-south direction, and characterized by Precambrian rocks comprising basic/ Ultrabasic and other older basement gneisses which form crustal scale shear zones extending for about 150 Km along its strike (Worku., et al., 1989). The belt is known for gold and other metallic and industrial minerals. The objective of this research is to use geological and structural mapping of the area and core logs to establish the inter-relationship between lithology and structure and to assess its control on the Okote gold deposit. Inorder to do that a pre-field study of the area using different literatures and reports was done, then during field work different kind of data collected like geological and structural mapping with important samples to identify the mineral assemblage of the area was done and after field works these gathered data from different literature and data from field work were used aiming to form a relationship between the data gathered to output the conclusion. The main rock units of the study area are chlorite-amphibolite schist, chlorite-carbonate schist, meta-gabbro, talc tremolite actinolite schist, granodiorite and quartz veins. The most common types of alteration in the area are; porpylitic alteration (includes Chloratization, Carbonitization and Epidotization), Pyritization, Silicification, Tourmalinization, and in small amount sericitization and feldspatization. The rocks of the study area has two kinds of strain, brittle and ductile strains which implicates the deformation takes place in the area is the same as that of the strain measurements of other localities. Gold in the study area is mainly related to chlorite-carbonate shist and meta-granodiorite. The ore body also relates to wall rock alteration like pyritization, carbonation and silicification. These ore bodies are confined by or found adjacent to the brittle-ductile shearzones These results implicates that the gold occurrence of Okote is controlled by lithologies and structures.
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Relationship Between Structure, Lithology, Control on Gold Mineralization, Okote Area, Southern Ethiopia