Abstract:Qitianling granites are located in southern Hunan. Recent geological survey shows that there exists a superlarge tin polymetallic deposit there. The contents of major, minor, and rare earth elements of Qitianling granites were analyzed by ICP-AES and ICP-MS. The contents of major elements indicate that these granites are of metaluminous type characterized by rich Si, Al and alkali and poor Mg and Fe, suggesting that they might have experienced remarkable crystal differentiation. The contents of rare earth elements (REE) are rather high, being 199.28×10-6～448.34×10-6 (307.03×10-6on average) and characterized by rich light REE and poor heavy REE. In addition, these granites are obviously rich in large lithophile elements, especially rich in Rb and Th, but poor in Ba, Nb, Ta, Sr, P, Eu and Ti, implying that the source of the granites might have derived from crust rocks. Based on a comparison between Qitianling granites and Qianlishan granites, this paper points out that granites in these two places have similar geochemical features. Furthermore, the genesis, age and mineralization of Qitianling granites are discussed. The formation of superlarge Sn-polymetallic deposits might have caused by the ascending of the mantle which resulted in the remelting of crustal materials together with hydro-thermal activity under the Jurassic extensional setting, which led to the enrichment of metal elements.
