Structural Relationships, Petrographic Characteristics and Bulk Geochemistry of Chromite Mineralization in the Balıköy–Tavşanlı Ophiolitic Rocks, NW Türkiye

Abstract Chromitites hosted by ophiolitic ultramafic rocks record melt–rock interaction and mantle processes, yet their present-day geometry may be substantially modified by tectonic deformation and serpentinization. This study documents the Balıköy–Tavşanlı chromite occurrence in northwestern Türkiye through integrated field mapping, structural observations, petrography, ore microscopy and bulk X-ray fluorescence (XRF) geochemistry. The mineralization is hosted predominantly by variably serpentinized dunite and is concentrated in three approximately parallel NW–SE-trending zones that dip about 45° northwestward and broadly parallel the regional thrust architecture. Chromite occurs as disseminated, spotted/leopard, banded–lenticular and massive aggregates. Fracturing, fragmentation, brecciation and cataclastic textures are common, while the host-rock matrix contains serpentine, talc and locally secondary carbonate, albite and Fe-oxide phases. Nine bulk-ore samples contain 27.79–41.18 wt% Cr, 40.62–60.19 wt% Cr₂O₃ and 4.50–9.44 wt% Fe; reported Cr/Fe ratios range from 3.31 to 7.95. The spatial correspondence between mineralized zones and thrust-related structures documents a strong structural relationship, but does not demonstrate syn-thrust chromite formation. The most conservative interpretation is that deformation modified the present geometry and textures of pre-existing chromite-bearing bodies. The study provides a field-based framework for exploration while distinguishing observed surface relationships from unverified subsurface continuities and unresolved genetic interpretations.