A comparative study of the Indosinian W-and Sn(Sn-W)-bearing granites in South China
In order to reveal the genesis and magmatic natures of Indosinian granites associated with the W and Sn mineralization in South China,a series of geochemical data of the Indosinian W and Sn(Sn-W)mineralization associated granites in South China were collected and statisticly analyzed in this paper.The results show that those Indosinian granites all belong to the highly differentiated high-K peraluminous subalkaline series and they are mainly S-type granites with minor I/A-type granites.The ore-forming granites were mainly sourced from the crust composed of argillaceous/clayey metamorphite.The eNd(t)values of the W-and Sn-bearing granites are higher than that of the South China crust,indicating that their magmatic sources could be influenced partly by the mantle materials.The W-bearing granites have relatively young T2DM ages comparing with the Sn(Sn-W)-bearing granites,indicating that the source of W-bearing granites could be relatively young crust or could be influenced by more mantle materials.Moreover,comparing to the W-bearing granite,the Sn(Sn-W)-bearing granite belongs to the relatively reduced ilmenite series granite,indicating that the magma with relatively low oxygen fugacity could be conducive to the Sn enrichment and mineralization.The W-bearing granites have lower zircon saturation temperatures than the Sn(Sn-W)-bearing granites.This may be caused by the difference between melting temperatures of source materials with respectively enriched Sn and W.This also explains why Indosinian W and Sn deposits in South China occurred as respective W polymetallic deposits and Sn(Sn-W)polymetallic deposits distributed in different districts of South China.
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万方数据
