Alteration geology and geochemistry of Kesikköprü (Bala, Ankara) Fe-skarn deposit

This study investigates the mineralogy of skarn, ore, and wall rocks in the Kesikköprü Fe-skarn deposit, along with the behavior, distribution, and enrichment processes of major oxides and trace elements. It also evaluates the skarn-forming potential of the Kesikköprü granitoid for different metals. The Kesikköprü mineralization is linked to an endoskarn zone dominated by garnet-pyroxene (±phlogopite±epidote) and to an exoskarn zone, in which assemblages toward the wall rocks comprise garnet (±pyroxene±phlogopite), pyroxene (±garnet±phlogopite±epidote), epidote-garnet, and epidote. Magnetite mineralization is particularly found within the epidote-garnet and epidote exoskarn subzones. Mineralogical and geochemical data indicate a significant increase in iron content during the late stages of skarn formation. Geochemical and isocon-mass balance analyses demonstrate a strong protolith control on skarn formation. In the granitoids, the endoskarn formation is characterized by Ca-Fe-Mg-Mn-Si addition with Al and alkalis (Na, K) depletion, whereas marbles record Ca depletion accompanied by increasing Fe input toward the ore zones. Based on the genetic link between skarn-forming granitoids and associated metal types, the Kesikköprü granitoid is inferred to have the potential to generate not only Fe-skarns but also Cu- and partially Au- and Pb-Zn skarns. Given the regional mineralization, these findings suggest that the Kesikköprü granitoid has multi-metal potential worthy of further exploration.