Indosinian W-Sn mineralization event in the Xikeng deposit, southern Jiangxi Province, Nanling Range: Evidence from U-Pb geochronology and Hf isotopes

The Chongyi-Shangyou-Dayu ore-concentrated district represents one of the most important wolframite production bases in China, and most of the W-Sn deposits formed in the early Yanshanian period. The Xikeng quartz vein-type W-Sn deposit is located spatially not far from the Triassic Keshuling granitic pluton. The deposit contains 43 ore-bearing quartz veins, in which the ore minerals are mainly cassiterite and wolframite. These ore veins are concentrated in the Sinian metasandstone and sandy slate of the Laohutang Formation and extend down to the top of the concealed granite. The concealed intrusion is composed of medium- to fine-grained muscovite granites, which relate to the Indosinian Keshuling granite, according to geophysical data. Zircon grains from the concealed Xikeng granitic intrusion have a concordant U-Pb age of 232.1 +/- 1.1 Ma (MSWD = 0.9). The zircon epsilon Hf(t) values range from -11.0 to -7.9, indicating primary reworking of the ancient crustal materials. Wolframite and cassiterite grains yield Tera-Wasserburg concordia intercept ages of 228.4 +/- 0.9 Ma (MSWD = 1.2) and 227.8 +/- 1.6 Ma (MSWD = 0.3) for the Xikeng deposit, respectively. These data demonstrate that the Indosinian W-Sn mineralization events were genetically related to granitic magma activities that share similar magmatic sources with the Yanshanian W-Sn mineralization-associated granitic intrusions. Combined with previous robust granitic and metallogenic ages, this paper identifies a new Indosinian W-Sn mineralization event in southern Jiangxi Province, Nanling Range.