PORPHYRY-TYPE MOLYBDENUM DEPOSITS IN THE EASTERN QINLING MO BELT, CENTRAL CHINA

The Eastern Qinling mineralizing belt of porphyry-type Mo deposits is located in the south margin of North China Platform. About 40% explored Mo resources of China are stored in that belt. Mo mineralization is related with Yanshanian （161-104Ma） small intermediate to acidic porphyry bodies. As the porphyry bodies intruded into Archean to middle Proterozoic carbonate rocks and alumino-silicate rocks, porphyry-type, sham-type and hornfels-type Mo ores were formed with different types of wallrock alteration. Ore-forming fluids are characterized by H2O-CO2-NaCl with lower to middle saline （0-l2.7% NaCl）. Oxygen and hydrogen isotope data suggest that ore-forming fluid of the early stage is mainly magmatic water. Along with evolution of mineralization to late stage, ratio of magmatic water decreased and meteoric water added.