Alteration and mineralization in Kalkafi granitoid intrusive body, northeast of Anarak

Kalkafi area is located about 76 km northeast of Anarak (Isfahan Province), in Central Iran structural zone. Based on field observations, petrographical and XRD examinations, three major alteration zones were identified in the studied area including potassic, phyllic-argillic, and silicic zones. Potassic alteration is characterized by orthoclase + biotite + quartz ± sericite assemblage. Phyllic alteration is composed of sericite + quartz + pyrite associated with clay minerals ± calcite, and argillic alteration is characterized by kaolinite + dikite + sericite + quartz + hematite + limonite + goethite. Two major ore mineralization were identified in the studied area: (1) Cu-Mo mineralization and (2) Au-Pb-Zn polymetallic mineralization. Cu-Mo mineralization is mainly related to porphyry quartz monzonites and granites. Chondrite normalized REE patterns of unaltered intrusive bodies (quartz monzonites) indicate a‎ strong LREE and a weak HREE differentiations. Lower content of total REEs in‎ the altered samples of the studied area indicates their mobility in hydrothermal environment. Microthermometric analysis of fluid inclusions of the studied samples indicates that salinity of mineralizing fluid ranges from 1.74 to 21.11 NaCl equivalent wt%. Collected homogenization temperatures confirm the existence of at least two generations of fluid inclusions or mineralizing fluids in this area.