Tracing magma mixing in granite genesis

In situ U - Pb dating and Hf-isotope analysis of zircons

Jin Hui Yang*, Fu Yuan Wu, Simon A. Wilde, Lie Wen Xie, Yue Heng Yang, Xiao Ming Liu

*Corresponding author for this work

Research output: Contribution to journalArticle

418 Citations (Scopus)

Abstract

In situ zircon U-Pb and Hf-isotopic data have been determined for mafic microgranular enclaves and host granitoids from the Early Cretaceous Gudaoling batholith in the Liaodong Peninsula, NE China, in order to constrain the sources and petrogenesis of granites. The zircon U-Pb age of the enclaves (120 ± 1 Ma) is identical to that of the host monzogranite (120 ± 1 Ma), establishing that the mafic and felsic magmas were coeval. The Hf isotopic composition of the enclaves [ξHf(t) = +4.5 to -6.2] is distinct from the host monzogranite [ξHf(t) = 15.1 to -25.4], indicating that both depleted mantle and crustal sources contributed to their origin. The depleted mantle component was not previously revealed by geochemical and Nd and Sr isotopic studies, showing that zircon Hf isotopic data can be a powerful geochemical tracer with the potential to provide unique petrogenetic information. Some wall-rock contamination is indicated by inherited zircons with considerably older U-Pb ages and low initial Hf isotopic compositions. Hafnium isotopic variations in Early Cretaceous zircons rule-out simple crystal - Liquid fractionation or restite unmixing as the major genetic link between enclaves and host rocks. Instead, mixing of mantle-derived mafic magmas with crustal-derived felsic magmas, coupled with assimilation of wall rocks, is compatible with the data.

Original languageEnglish
Pages (from-to)177-190
Number of pages14
JournalContributions to Mineralogy and Petrology
Volume153
Issue number2
DOIs
Publication statusPublished - Feb 2007
Externally publishedYes

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