Abstract:Based upon the probable source materials from which the granites might have been derived and the geological setting against which they occur, the authors hold the opinion that the Mesozoic granites in southeastern China may be divided principally into two genetic series, namely, the transformation series and the syntexis series. The former appears in a well-developed crust inside the continental plate while the latter is found in the active continental margin and along some deep fault zones and fault depressions inside the continental plate. As these two series of granites represent different stages of crustal development and different degrees with which they connect with the upper mantle, and as marked differences exist between the crust and the upper mantle in the distribution of metallic elements, it is considered that granites of the transformation series were formed in the well-developed continental crust and are characterized by deposits of tungsten, tin, tantalum, etc., whereas those of the syntexis series were formed in a transitional crust and are characterized by iron, copper, and molybdenum deposits. And, the least developed crust might give birth to the mantle-derived granites, characterized by ∑Ce and niobium metallic ores. At the end of this paper, a discussion is given about the relationship between the subduction of the pacific plate and the formation of the different genetic series of the Mesozoic granites in southeastern China. In addition, some petrological peculiarities of the two genetic series of granites are described in detail. The transformation series comprise mainly normal granites whereas the syntexis series commonly vary from diorites quartz diorites→granodiorites→quartz monzonites→potash granites. In petrochemistry, their chief differences are: (l)K2O-SiO2 in the syntexis series exhibits a linear relation, and K-70 (percentage of K2O when SiO2 content is at 70%) increases from the seacoast toward the inland, but K2O-SiO2 in granites of the transformation series possesses no linear relation; (2) K2O/Na2O ratios of the syntexis series are small compared with those of the transformat/on series, and show tendency to increase toward the inland; (3) the relation of K2O+Na2O-SiO2 shows an increase in alkalinity toward the inland, (4) as to the accessories, the syntexis series distinctly contains more magnetite, idocrase and other calcium-bearing accessories, whereas the transformation series is characterized by calcium-poor accessories; and (5) the trends of evolution of the multi-staged granites of these two series are different in such a way that rocks of the syntexis series evolved from originally soda-rich varieties to potash-rich ones. whereas those of the transformation series from originally potash-rich ones to soda-rich ones toward the latest stages.
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徐克勤, 胡受奚, 孙明志, 叶 俊.1982.华南两个成因系列花岗岩及其成矿特征[J].矿床地质,1(2):1~14.1982.On the two genetic series of granites in south-eastern China and their metallogenetic characteristics[J].Mineral Deposits1(2):1~14
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