从云母微量元素特征探讨华南花岗岩的成因和演化

云母中微量元素可分为浅源指示元素和深源指示元素。浅源指示元素Nb、Ta、Sn、Li、Rb在南岭系列云母中的含量高于长江系列,而深源指示元素Co、Ni的含量长江系列大于南岭系列。云母中Nb、Ta、Sn、Li、Rb变化特征是自身成矿演化的直接示踪剂,而Co、Ni变化特征是Fe、Cu、Au、Mo(W)、Pb、Zn成矿演化的重要示踪剂。云母中Cu、Zn、W、Mo、U、Th等元素呈波动性变化,不能灵敏指示花岗岩的成因与演化。微量元素在云母中的选择分布主要受岩浆物源化学背景的制约,同时也受岩浆侵位和分异演化程度高低以及结晶的物理化学条件变化等因素的影响。

ON THE ORIGIN AND EVOLUTION OF GRANITES IN SOUTH CHINA IN TERMS OF TRACE ELEMENTS IN MICAS

Trace elements in micas from granites can be divided into two groups: one is indicatory of shallow-source material and the other of deep-source material. The contents of indicatory elements such as Nb, Ta, Sn, Li and Rb for shallow-source material in micas from the Nanling series granites are higher than those in micas from the Yangtze series granites, whereas the contents of indicatory elements such as Co and Ni for shallow-source material in micas from the Nanling series are less than those in micas from the Yangtze series. On account of their variation trend, the trace elements Nb, Ta, Sn, Li and Rb in micas can be used as an indicator for their own mineralization, but Co and Ni as an indicator for Fe, Cu, Au, Mo (W), Ph, Zn mineralizations. The clements Cu, Zn, W, Mo, U and Th in micas are irregularly variable, and hence cannot be used as sensitive indicators for the genesis and evolution of granites. The selective distribution of trace elements in micas is controlled mainly by the emplacement, evolution and crystallization of the magma.