On the classification of granitic rocks based on whole-rock Sr and Yb concentrations III: Practice.
三论花岗岩按照Sr-Yb的分类:应用

In this study, we test the reliability of new classification of granitic rocks based on Sr and Yb concentrations of granitic rocks that we suggested in our previous study (Zhang et al., 2010a). A large data set of granitic rocks worldwide including those from Qaidam, the North Qilian, the Inner Mongolia, Songpan-Ganze, the Dabei Mountains, the Taihang Mountains, and Paleoproterozoic granitic rocks in the North China and Neoproterozoic granitic rocks in South China Blcok, and those from Turkey, Russia, Brazil, Congo, Bohemia and Italy are used to examine the relationship of the Sr and Yb concentrations of granitic rocks and their formation pressure and depth. The data indicate that the variation of granitic rocks in Sr and Yb concentrations is closely related to the pressure when they formed, which can be used to estimate the variation of the thickness of the crust. Such as the Paleoproterozoic granites in the North China by this method to study, not found in central North China Craton occurred collision in the Paleoproterozoic. Therefore, the North China Craton was divided into two blocks need to be further re-understanding. Another example is the the Neoproterozoic granite in South China Block. Our study shows that crust of the South China Block is thin during the Neoproterozoic, and however, it seems irrelevant with rifting-reakup of the supercontinent Rodinia. The data also indicate that the different mineralization associated with granitic rocks is also related to pressure. Cu-Au mineralization is commonly hosted in adakitic-type and Himalaya-type granitic rocks which likely formed from thickened lower crust, whereas W-Sn mineralization is usually hosted in Nanling-type granitic rocks which formed from shallower crust. However, such classification based on Sr and Yb concentrations of granitic rocks needs more test in both practice and theory before it can be accepted by confidence.