THE ROLE OF THE STRUCTURES ON THE FLUORITE MINERALIZATION: INSIGHT TO FLUID INCLUSION AND ALTERATION MAP OF THE LAAL-KAN FLUORITE DEPOSIT, NW IRAN

Fluorite mineralization is controlled by the multiple geological processes such as structural control, geochemical characterization of hydrothermal fluids, temperature and depth. The mineralization associated with the alteration of the host rocks and trapping of fluid in the host rock crystallographic defects. Alteration in the host rocks due to circulation of hydrothermal fluids and several techniques were applied to discriminate the associated alterations in fluorite deposition using the ASTER images. The resulting images indicated that the fluorite mineralization in the studied area accompanied by propylitic and phyllic alterations. The results of micro-thermometry analysis of the fluorite hosted fluid inclusions indicated that the maximum homogenization temperature was 253 degrees C. These data implies that the temperature of hydrothermal fluids probably had an essential role in the propagation of the alteration zones. The depth versus homogenization temperature diagram for fluorite mineralization in the studied district revealed that the depth of fluorite mineralization varies between 33 to 256 m. Two fluorite generations were distinguishing in the study district. The first generation is characterized by high salinity (18-25 wt.% NaCl) which developed on the deeper level and along the fault zone. The second generation is characterized by low salinity (6-13 wt.% NaCl) on shallow depth and deposited in the fractures. The results revealed that fluorite deposition was not contemporaneous with host rock deformation and deposited in the late-stage deformation phase.