Micrometallogeny and hydrothermal fluid evolution of the Iju porphyry Cu deposit, NW Kerman, Iran: Evidence from fluid inclusions, Laser Raman spectroscopy, and S-O isotope systematics

The Iju Cu porphyry is located in the NW part of the Kerman Magmatic Copper Belt (KMCB). It is related to a -9 Ma granodiorite porphyry intrusion, with three main stages of hydrothermal activity. The homogenization temperatures for the fluid inclusions are in the ranges of 200-494 degrees C, and their salinities vary from 4.0 to 42.8 wt % NaCl equiv., which are typical magmatic-hydrothermal fluids. The & delta;34S values of sulfides range from-0.4 to +3.2 %o (V-CDT), and the & delta;34S values of anhydrite samples range from +11.6 to +16.8 %o. The & delta;34S values of sulfides show a narrow range, implying a homogeneous sulfur source. The oxygen isotopic composition of hy-drothermal water in equilibrium with quartz samples ranges from +3.4 to +6.0 %o (V-SMOW) consistent with the hydrothermal fluids having a magmatic signature, but diluted with meteoric waters in the main mineralizing stage. The most important factors responsible for metal precipitation in the Iju porphyry deposit are fluid boiling, oxygen fugacity decrease and cooling followed by dilution with meteoric water. The primary fluids of the Iju Cu deposit are characterized by relatively high temperature and moderate salinity, and are CO2-rich, indicating a typical post-collisional porphyry system.