Abstract:
Objective Since the discovery of the Weilasituo rare metal−tin−polymetallic deposit in Inner Mongolia, the genesis of its ore deposits has been a central focus of geological inquiry. Oxygen fugacity (f_\mathrmO_2 ) has been identified as playing a pivotal role in the processes of tin element migration and enrichment. Accurate characterization of f_\mathrmO_2 in granites is essential for constraining the genesis of the Weilasituo tin polymetallic deposit.
Methods This study employs LA−ICP−MS zircon U−Pb dating, whole−rock geochemical analyses, and zircon trace element studies to investigate granites closely associated with mineralization at the Weilasituo deposit.
Results Zircon U−Pb dating reveals concentrated crystallization ages of the granites at approximately 120.2±1.6 Ma and 125.9±1.9 Ma, indicative of multiple magmatic episodes in this area. Zircon trace element analyses show that the Ce/Ce* average value for granites at Weilasituo is 400.87, with an average Eu/Eu* value of 0.062. The \mathrmlogf_\mathrmO_2 predominantly ranges from −26 to −20, and ΔFMQ values are concentrated between −6 and −1, suggesting a predominantly reducing ore−forming environment. The obtained age data closely align with previously proposed late−stage magmatic activity, indicating that these ore−forming magmas retained low f_\mathrmO_2 characteristics.
Conclusions In summary, it is concluded that oxygen fugacity is the key factor controlling the formation of Verastor deposit. The low oxygen fugacity of Verastor metallogenic magma inhibits the premature saturation of Sn in the deep crust, which enables Sn to accumulate in the magma and eventually form large−scale Sn mineralization.
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