A discussion on the source and nature of initial ore-forming fluids of the Zijinshan deposit in Fujian province: Evidence from REE and trace elements

The source and nature of ore-forming fluids constitute an important basis for determining prospecting orientation and establishing the model of prospecting prediction for magmatic hydrothermal deposits. The authors have found that ores and granodiorite-porphyry are similar to each other in REE characteristics, as shown by a comparative analysis of major plutons and typical ores, and that the formation age of granodiorite-porphyry pluton is so closed to metallogenic time, thus the pluton could provide enough heat for the ore-forming fluids. It is thus inferred that magmatic hydrothermal fluids were derived from deep concealed granodiorite-porphyry pluton, which served as the original source of ore-forming fluids. The high field strength elements (HFSE) (Th, Nb, Ta, Zr, Hf, etc.) of ores are relatively high with enrichment of LREE, and HFSE/LREE ratios (Hf/Sm, Nb/La) are higher than 1, suggesting that F is richer than Cl in ore-forming fluids. On such a basis and in combination with a lot of previous researches, the authors have established a model for ore-prospecting prognosis along Ermiaogou-Zhongliao section.