Neoproterozoic tungsten mineralization: Geology, chronology, and genesis of the Huashandong W deposit in northwestern Jiangxi, South China.

The Huashandong W deposit (7.7 Mt @ 0.26% WO3) is a newly discovered Neoproterozoic scheelite-dominated deposit in the world-class Jiangnan tungsten belt, South China. It occurs largely in metasedimentary rocks near the western margin of the Neoproterozoic Jiuling batholith and mainly consists of W-bearing exogreisen, hydrothermal breccias, and quartz veins. Two episodes of Neoproterozoic granite magmatism are identified with zircon U-Pb ages of ca. 830–823 and 807–804 Ma, respectively. According to cross-cutting relationships and mineral assemblages, two periods of hydrothermal alteration and W mineralization, corresponding to the two episodes of granite magmatism, are recognized in the Huashandong deposit. The early period is dominated by greisenization and associated scheelite mineralization whereas the late period is characterized by sericitization, hydrothermal brecciation, quartz veining, and associated scheelite and minor wolframite mineralization. Molybdenite Re-Os dating indicates that the early- and late-period W mineralization took place at ca. 828 and 800 Ma, respectively. Zircon trace element characteristics suggest that the Jiuling granite crystallized from reduced granitic magmas and has the potential for W mineralization. The petrologic and geochemical features of the Jiuling granite, coupled with the zircon U-Pb ages and Hf isotopic signatures and molybdenite Re-Os ages, imply that the Huashandong W deposit is genetically related to two phases of evolved granodiorites in the Jiuling batholith. The magmatic-hydrothermal nature of both metallogenic events is confirmed by H-O isotopes on hydrothermal quartz. [ABSTRACT FROM AUTHOR]