Petrography, geochemistry and formation of the Sarıçimen (Van, eastern Türkiye) Fe-Ni-Co laterite deposit

The Sarıçimen Fe-Ni laterite deposit is located in eastern Türkiye (Van province) and represents one of the important Ni and Co-enriched lateritic mineralizations formed in the ophiolitic occurences. This study aims to decipher the petrographic and geochemical signatures of the laterite horizon in order to better figure out the processes controlling Fe-Ni-Co mineralization and the genesis of the deposit. In this study, field and petrographic observations, and whole-rock geochemical data have been used to characterize the mineralogical and geochemical evolution of the lateritic horizon. Petrographic studies indicate that the protolith of the laterite zone is mostly composed of serpentinized ultramafic rocks including relics of Cr-spinel and chromite grains. This lateritic zone is characterized by hematite-and magnetite-rich zones formed above saprolitic levels that may have been derived from the weathering of ultramafic parent rocks. Whole rock geochemical analyses indicate that Fe₂O₃ and SiO₂ are the dominant oxides, and Ni concentrations vary between 0.33 and 1.01 wt.%. Also, Co values are ranging between 330 ppm and 600 ppm in the laterite samples investigated here. More importantly, correlation analyses exhibit a positive relationship between Ni and Fe₂O₃ and this may be attributed to a close association with Fe-oxide minerals during the lateritization. In contrast, a negative correlation between Ni and SiO₂ may indicate the presence of silica depletion during chemical weathering. The geochemical trends investigated here reveal that the laterite zone developed through intense lateritic weathering of ultramafic rocks, which is characterized by the removal of relatively mobile elements such as Si and Ca and the residual enrichment of Fe, Ni, and Co. The presence of Cr-spinel relics once again confirms the ultramafic origin of the parental rocks. Overall, the Sarıçimen deposit represents a Fe-Ni-Co laterite derived from nearby ultramafic sources within the ophiolitic sequence. The occurrence of Fe-Ni-Co laterite deposits at both the southwestern and northeastern segments of the Southern Neotethys Suture Zone suggests that this tectonic belt may represent a promising metallogenic area for lateritic Fe-Ni-Co mineralization in the southern Türkiye.