Magma mixing of granites at Lianghe： In-situ zircon analysis for trace elements, U-Pb ages and Hf isotopes

• Published in: Science China. Earth sciences Vol. 54; no. 9; pp. 1346 - 1359
• Main Authors: Cong, Feng, Lin, ShiLiang, Zou, GuangFu, Li, ZaiHui, Xie, Tao, Peng, ZhiMin, Liang, Ting
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science China Press 01-09-2011; Springer Nature B.V
• Subjects: Cretaceous; Earth and Environmental Science; Earth science; Earth Sciences; Granite; Hf同位素; Isotopes; Magma; Minerals; Research Paper; Trace elements; 中微量元素; 原位分析; 地梁; 岩浆混合花岗岩; 年龄; 锆石; China, People's Rep; trace element; Lianghe; zircon; magma mixing; U-Pb age; Hf isotope
• ISSN: 1674-7313; 1869-1897
• DOI: 10.1007/s11430-011-4208-z

In this paper, we report an integrated study of trace element, U-Pb age and Hf isotopic composition of zircons from alkali feldspar granites, granodiorites and diorite enclaves in a recently discovered ring complex at Lianghe in western Yunnan, China. The granitoids showed identical U-Pb ages of 127, 115 and 122 Ma, from felsic to mafic, but had different zircon trace elements and Hf isotopic compositions. Trace element content decreased with a gradual increase in εHf（t） values of -9.1 to -5.4, -4.5 to 0, and 3.6 to 6.2, respectively. Results indicate that changes in zircon trace elements generally correlate with changes in Hf isotope signatures within single samples and among various granitoids. These relationships reflect the mixing of felsic and mafic magmas. Evidence indicates that depleted mantle-derived mafic magma underplating caused ancient crustal melting, and then formed large-scale granites in Lianghe during the Early Cretaceous. These granodiorites were formed mainly by the mixing of mafic magma and granitic magma.