| Affiliation: | WANG Xiang1,2, W. L. Griffin2, WANG Zhicheng1 & ZHOU Xinmin1 1. Department of Earth Sciences and State Key Laboratory for Mineral Deposit Research, Nanjing University, Nanjing 210093, China; 2. GEMOC Key Center, Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, Australia |
| Abstract: | In the peralumineous granite of Yajiangqiao zircon population can be divided into two groups (i.e. Zircon Ⅰ and Zircon Ⅱ), which were formed in magmatic chamber and in emplacement place, respectively. The Hf isotope compositions of two stages of zircon show that the host magma was essentially derived from crustal material by melting. However, some higher 176Hf/177Hf ratios indicate that the granitic zircons should contain fine crystal of zircon formed in mantle-derived magma. In fact, the backscattered electron imaging and the electron microprobe analysis reveal that there is another type of zircon included within Zircon Ⅰ, which is quite different from Zircon Ⅰ and Zircon Ⅱ in morphology and chemistry. They are considered to be the product of the mantle-derived magma intruded into the granitic magma chamber at the beginning of anatexis. Thus, it is suggested that the formation of Yajiangqiao granite is related to the underplating of mantle magma. |
