Mineralogical characteristics and geological significance of the Zhuxi Cu-W polymetallic ore deposit, Jiangxi Province

The Zhuxi Cu-W polymetallic ore deposit is located in the northwest of Gandongbei faulted zone. The orebodies mainly occur in the skarn and skarnized marble at the contact zone between Yanshan intrusive rock and carbonate. Typical skarn minerals consist mainly of garnet, diopside, tremolite, wollastonite, serpentine, phlogopite, vesuvianite and chlorite. According to the association and metasomatism relationship of the minerals, the authors infer that the ore-forming fluid might have experienced five evolutionary stages, i.e., skarn stage, degenerate alteration stage, quartz sulfide stage, quartz carbonate stage, and supergene oxide stage. Electron microprobe analyses show that the garnet is mainly composed of grossularite-andradite, the pyroxenes mainly belong to diopside-andradite series, the amphiboles show characteristics of calciferous amphibole, and the chlorites are mainly pycnochlorite and clinochlorite. It is also inferred that after the intrusion ore-forming the fluid was under the medium-acid to acid and weak oxidizing conditions at the skarn stage. At the degeneration alteration stage, the scheelite was separated out after the rise of the oxygen fugacity and the pH. The metal sulfides precipitated along with the drop of the oxygen fugacity. The class of the metal mineralization was also inferred according to its mineral compositions.