Geochronological, geochemical, and whole-rock Sr-Nd isotopic analyses were performed on a suite of Palaeozoic nepheline syenites from Zijinshan to characterize their ages and petrogenesis. Laser ablation inductively coupled plasma-mass spectrometry U-Pb zircon analyses yield consistent ages of 525.7 +/- 2.8 million years for a sample (HYK01). These intrusive rocks belong to the foid syenite magma series in terms of K2O + Na2O contents (14.3-15.2 wt.%) and to the shoshonitic series based on their high K2O contents (5.42-5.61 wt.%). The nepheline syenites are further characterized by high light rare earth element contents [(La/Yb) N = 29.1-36.1]; show modest negative Eu anomalies (delta Eu = 0.5-0.6) and positive anomalies in Rb, Th, U, Pb, Zr, and Hf; are depleted in Ba and high field strength elements (P and Ti). In addition, all the nepheline syenites in this study display relatively low radiogenic Sr (Sr-87/Sr-86)(i) (0.7042-0.7043) and positive epsilon(Nd) (t) (0.7-0.8). These results suggest that the nepheline syenites were derived from depleted continental crust. The parent magmas likely experienced fractional crystallization of plagioclase, Ti-bearing oxides (e. g. rutile, ilmenite, and titanite), apatite, and zircon during ascent, with negligible crustal contamination before final emplacement at a high crustal level.

Publication name	INTERNATIONAL GEOLOGY REVIEW　Volume:54　Issue:11　Pages:1296-1308　Published:2012
Author(s)	Liu, Shen; Hu, Ruizhong; Gao, Shan; Feng, Caixia; Coulson, Ian M.; Feng, Guangying; Yang, Yuhong; Qi, Youqiang; Yang, Chaogui; Tang, Liang
Corresponding author	LIU Shen  liushen@vip.gyig.ac.cn  Chinese Acad Sci, State Key Lab Ore Deposit Geochem, Inst Geochem, Guiyang 550002, Peoples R China.

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