地质学报2017，Vol.91Issue(12)：2667-2678,12.
西昆仑造山带东段阿拉玛斯岩体Pb-Hf同位素组成特征、岩石成因及源区特征
Pb-Hf Isotopic Compositions of Granitoids and Petrogenesis of the Alamas Pluton in the Eastern Part of the West Kunlun Orogen and Its Provenance Characteristics
摘要
Abstract
The source of granitic magma was complex in the post-collision stage and needs to be further studied by using various isotope methods.The Alamas granitoids is distributed in the eastern section of the West Kunlun orogenic belt and of important significance for understanding the continental growth evolution after the closure of the Proto-Tethys.Previous studies have shown that the Alamas granitoids was the product of partial melting of an ancient,deep crustal source in the post-collision stage.In order to understand the source characteristic of the Alamas granitoids,Pb-Hf isotopic compositions of the granitoids were analyzed.The results show that the εHf(t) values range from-9.5 to-3.2 (averaging-5.6) and the two stage Hf model ages range from 1633Ma to 2028 Ma,indicating that the Alamas pluton likely sourced from the partial melting of an ancient,deep crust.The granitoids have 206Pb/204Pb values between 18.382 and 19.333 (averaging 18.784),207Pb/204pb values between 15.589 and 15.642 (averaging 15.614),208Pb/204Pb values between 38.585 and 39.080 (averaging 38.800),μ values from 9.45 to 9.48 (averaging 9.46),and ω values from 33.80 to 38.14 (averaging 36.16).In the discrimination diagram,these samples are plotted mostly in the field of the upper crust rocks,indicating that the source area of the Alamas pluton is characteristic of high Pb isotope.Therefore,addition of a minor amount of high Pb isotopic material (sediments) into magmatic source resulted in diversity of material source for formation of the Alamas pluton in the post-collision stage.关键词
Pb同位素/Hf同位素/花岗岩类/阿拉玛斯/西昆仑Key words
Alamas granitoids/Tibet/Western Kunlun Orogen/Pb isotopes引用本文复制引用
张其超,吴珍汉,李侃,黄河,刘琰,刘志伟,周清,金谋顺,倪晋宇..西昆仑造山带东段阿拉玛斯岩体Pb-Hf同位素组成特征、岩石成因及源区特征[J].地质学报,2017,91(12):2667-2678,12.基金项目
本文为中国地质科学院中央级公益性基本业务费专项基金(编号:YWF201601)和中国地质调查局国土资源大调查研究项目(编号:DD20160004,DD20160083-1,12120115000801,121201101000150014)资助成果. （编号:YWF201601）
