Student Webinar by Siraj Beyan Mohamed

Western Ethiopia represents a critical segment of the southern Arabian–Nubian Shield, whereprolonged Neoproterozoic mantle–crust interaction, arc accretion, ophiolite emplacement,granitoid intrusion, and subsequent transpressional deformation collectively establishedfavorable physicochemical and structural conditions for gold mineralization, particularly withinregionally developed shear zone systems hosted by low-grade metavolcanic–metasedimentarysequences and spatially associated ultramafic complexes.The geodynamic evolution of the region is characterized by episodic mantle-derived magmainjection, crustal reworking, and progressive strain localization along first- and second-ordershear zones that acted as long-lived fluid conduits, enabling efficient transport of gold-bearingmetamorphic and magmatic-hydrothermal fluids. Variations in redox state, sulfur fugacity, andfluid composition, driven by interaction between oxidized crustal lithologies and reduced mantle-derived ultramafic rocks, played a fundamental role in controlling gold solubility, transport assulfur-complexed species, and eventual precipitation during pressure–temperature fluctuationsassociated with deformation.Two genetically distinct ultramafic suites, namely ophiolitic mantle fragments and Alaskan-typearc-related intrusions, reflect contrasting mantle sources, magma evolution histories, andtectonic settings, which in turn influenced their metallogenic fertility and styles of goldmineralization.Major gold occurrences, including those at Tulu Kapi, Kurmuk, Yubdo, Akobo, Segele, and Joru,demonstrate strong spatial and genetic links to shear-controlled fluid flow, ultramafic–felsiclithological contacts, and rheological contrasts that enhanced permeability duringtranspressional deformation.This synthesis highlights Western Ethiopia as a coherent geodynamic and metallogenicprovince in which the integration of mantle processes, crustal architecture, and structuralevolution fundamentally governed the localization, grade, and style of gold mineralization.