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
发布时间:2018-10-12 10:52
【摘要】:后碰撞阶段花岗质岩浆的源区多较为复杂,需要从多方面开展同位素的研究来加以识别,阿拉玛斯花岗质岩体位于西昆仑造山带东段。先前的研究表明阿拉玛斯岩体是后碰撞阶段下地壳部分熔融。为进一步研究阿拉玛斯花岗岩类的源区特征,本文对阿拉玛斯花岗岩类进一步进行Pb-Hf同位素的测定。结果显示:阿拉玛斯岩体具低的锆石εHf(t)值为-9.5~-3.2(平均值为-5.6),二阶段模式年龄为1633~2028 Ma,反映了岩浆来源于较老的下地壳部分熔融。阿拉玛斯岩体的206Pb/204Pb范围为18.382~19.333,平均值为18.784,207Pb/204Pb范围为15.589~15.642,平均值为15.614,208Pb/204Pb范围为38.585~39.080,平均值为38.800,μ值范围为9.45~9.48,平均值为9.46,ω值的范围33.80~38.14,平均值为36.16。在岩体源区判别图解上,样品主要落在上地壳的范围内,反映了阿拉玛斯岩体源区具有高Pb的同位素特征,说明岩浆源区有少量高Pb物质(沉积物)的混入,从而说明后碰撞阶段形成岩体的物质来源具有多样性。
[Abstract]:The source regions of granitic magma in post-collision stage are more complex and need to be identified by isotopic studies in many aspects. The Alamas granitic rock body is located in the eastern part of the West Kunlun orogenic belt. Previous studies have shown that the Alamas rock mass was partially melted in the lower crust during the post-collision stage. In order to further study the source characteristics of the Alamas Granitoids, the Pb-Hf isotopes of the Alamas granites have been further determined in this paper. The results show that the low zircon 蔚 Hf (t) value of Alamas is -9.5 ~ 3.2 (mean -5.6), and the two-stage model age of 1633 ~ 2028 Ma, reflects that the magma originated from the partial melting of the older lower crust. The 206Pb/204Pb range of the Alamas rock mass is 18.382 ~ 19.333, the average value is 15.589 ~ 15.642, the average value is 38.585N ~ (39.080), the average is 38.800, the 渭 value is 9.45 ~ 9.48, the average is 9.46, and the 蠅 value is 33.809 / 38.14, with an average value of 36.16. In the discriminant diagram of the source region of the rock mass, the samples mainly fall within the upper crust, which reflects the isotopic characteristics of high Pb in the source area of the Alamas rock body, indicating that there is a small amount of high Pb material (sediment) mixed in the magmatic source area. Therefore, the material sources of the rock mass formed in the post-collision stage are diverse.
【作者单位】: 中国地质科学院;中国地质调查局西安地质调查中心;中国地质科学院地质研究所;中国地质调查局成都矿产研究所;五矿勘查开发有限公司;
【基金】: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) 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
【分类号】:P588.1
本文编号:2265845
[Abstract]:The source regions of granitic magma in post-collision stage are more complex and need to be identified by isotopic studies in many aspects. The Alamas granitic rock body is located in the eastern part of the West Kunlun orogenic belt. Previous studies have shown that the Alamas rock mass was partially melted in the lower crust during the post-collision stage. In order to further study the source characteristics of the Alamas Granitoids, the Pb-Hf isotopes of the Alamas granites have been further determined in this paper. The results show that the low zircon 蔚 Hf (t) value of Alamas is -9.5 ~ 3.2 (mean -5.6), and the two-stage model age of 1633 ~ 2028 Ma, reflects that the magma originated from the partial melting of the older lower crust. The 206Pb/204Pb range of the Alamas rock mass is 18.382 ~ 19.333, the average value is 15.589 ~ 15.642, the average value is 38.585N ~ (39.080), the average is 38.800, the 渭 value is 9.45 ~ 9.48, the average is 9.46, and the 蠅 value is 33.809 / 38.14, with an average value of 36.16. In the discriminant diagram of the source region of the rock mass, the samples mainly fall within the upper crust, which reflects the isotopic characteristics of high Pb in the source area of the Alamas rock body, indicating that there is a small amount of high Pb material (sediment) mixed in the magmatic source area. Therefore, the material sources of the rock mass formed in the post-collision stage are diverse.
【作者单位】: 中国地质科学院;中国地质调查局西安地质调查中心;中国地质科学院地质研究所;中国地质调查局成都矿产研究所;五矿勘查开发有限公司;
【基金】: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) 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
【分类号】:P588.1
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