Browsing by Author "Ofgaa, Temesgen"

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    Some Features of Gold Mineralization i Worash in Southern Seken 1 Area (Worq Amba), Tigray
    (Addis Ababa Universty, 2000-06) Ofgaa, Temesgen; Getaneh, Worash (PhD)
    The geology of the study area is constituted by feldspar quartz sericite schist, muscovite chlorite schist , basic metavolcanics and granodiorite. The feldspar quartz sericite schist consists of thin intercalations of strongly silicified and chlorite talc schist . Additionally, granitic dykes and carbonate veins occur in this rock parallel to the regional foliation . The muscovite chlorite schist also has intercalations of quartz chlorite schist along its western margin. Major and minor quartz veins also occur in all major rocks. Foliations generally strike to the northeast and dip at moderate to steep angles to the west. Other geological structures evident in the study area include fractures and small tight folds. These folds may represent the earliest phase folds in the area . The rocks are strongly affected by hydrothermal alterations. Wall rock alteration types evident in the area include sericitization, silicification, carbonatization, chloritization, epidotization and sulfidation . Gold mineralization might have resulted from hydrothermal processes that caused the wall rock alterations. Open spaces along host rock fractures and foliations might have provided channel ways for the hydrothermal fluid. Gold has been detected in quartz and carbonate veins and altered feldspar quartz sericite schist, muscovite chlorite schist . The highest gold content has been obtained in chlorite talc schist that is intercalated in feldspar quartz sericite schist .Gold shows a slight positive correlation with cobalt. Though this result is not sufficient to suggest the source of the gold to be mafic- ultramafic rocks, it attracts attention for further studies in this regard . Some evidences from the granodiorite reveal that it is unlikely that the hydrothermal fluid emanated from this intrusive body.