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There are four episodes (Neoproterozoic, early Paleozoic, early and late Mesozoic) of Sn-W-Nb-Ta mineralization in South China, accounting for more than 50% W and 20% Sn reserves of the world and hosting considerable Nb and Ta resources. The genesis for such large-scale mineralization that may have seen multiple phases of recycling of ore elements is not well unterstood. The study of the earliest mineralized granites in South China, however, may be helpful to better understand the mechanism of mineralization. We present detailed mineralogical, geochemical, and isotopic data from two typical Neoproterozoic, mineralized intrusions, i.e., the Fanjingshan and Yuanbaoshan tourmaline leucogranites. There is a characteritstic mineral succession of diverse magmatic (columbite group minerals [CGMs], Nb-Ta-bearing cassiterite) and hydrothermal (wolframite, wolframoixiolite, Nb-Ta-poor cassiterite) Sn-W-Nb-Ta oxides. Hydrothermal cassiterite and W-bearing oxides (wolframite, wolframoixiolite) in the Yuanbaoshan intrusion were deposited separately by two types, i.e., Sn-rich and Nb-W-rich fluids. In-situ U-Pb dating of zircon, columbite and wolframoixiolite yields ages of 830 ± 5, 832 ± 5 and 821 ± 5 Ma, respectively. Whole-rock eNd(t) values of −2.5 to −6.4 correspond to crustal Nd model ages of 1.6–1.9 Ga. Paleoproterozoic model ages (~1.6–2.2 Ga) for most episodes of W-Nb-Ta mineralization in South China indicate that (i) Paleoproterozoic or older sediments may have been involved in the formation of W-Nb-Ta bearing granites and (ii) contributions of juvenile material was not important for these W-Nb-Ta mineralization. Neoproterozoic peraluminous granites along the Jiangnan Orogen formed in post-collision environments, but only those in the western part show Sn (-W-Nb-Ta) mineralization. The mineralized Neoproterozoic granites of the western part have experienced more extensive fractional crystallization (lower Nb/Ta, Zr/Hf ratios and more depleted in Fe, Mg, Ca, Sr, Ba, Eu, Ti) and are richer in volatiles (H2O, B) than the barren peraluminous intrusions of the eastern part. As similarly evolved Mesozoic metaluminous granites of the Nanling area have considerably more important tin mineralization than the mineralized Neoproterozoic granites, fractionation is not the only factor controlling mineralization. Instead, other factors, such as protolith and conditions of partial melting may account for the more important Mesozoic tin mineralization.

The Miao’ershan–Yuechengling granitic batholith (MYGB) in the west Nanling Range, South China, contains multiple intrusive phases including the Paleozoic porphyritic biotite granite and Early Mesozoic two-mica and muscovite granite associated with the W–Cu–U mineralization. In this study, the Gedongping granitic rocks, in the central part of the MYGB are shown to be related to Sn–Nb–Ta–Be mineralization. They comprise albite granite, pegmatite, and aplite, and intrude the Paleozoic granite. Sn–Nb–Ta oxide minerals such as cassiterite, columbite-group minerals, microlite and wodginite are common. Beryl occurs in the pegmatite and aplite. Zircon U-Pb isotopic data yielded an age of 153 ± 3 Ma for the formation of the aplite. In situ U-Pb dating of cassiterite from the albite granite and aplite yielded ages of 147 ± 5 and 155 ± 3 Ma, respectively, for the Sn mineralization. Geochemically, theses granitic rocks are rich in SiO2 (~72 wt%), Al2O3 (~15 wt%), and total alkali (~10 wt%), and the alumina saturation index is 1.0 to 1.1. Combined with the high HfO2 contents (up to 15.1 wt%) and low Zr/Hf ratios (6–35) in zircons, it is indicated that the Gedongping granitic rocks are highly evolved. We infer that the Gedongping granitic rocks underwent magmatic fractionation and subsolidus hydrothermal alteration, based on the textural and compositional variations of the Sn–Nb–Ta oxide minerals. Two fine-grained granite stocks within the MYGB, which were described as Late Mesozoic products, have been confirmed to form during the Paleozoic (420–426 Ma).