| 西藏北冈底斯巴尔达地区岩浆作用的成因:地球化学、年代学及Sr-Nd-Hf同位素约束 |
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| 引用本文： | 张亮亮,朱弟成,赵志丹,董国臣,莫宣学,管琪,刘敏,刘美华.西藏北冈底斯巴尔达地区岩浆作用的成因:地球化学、年代学及Sr-Nd-Hf同位素约束[J].岩石学报,2010,26(6):1871-1888. |
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| 作者姓名： | 张亮亮 朱弟成 赵志丹 董国臣 莫宣学 管琪 刘敏 刘美华 |
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| 作者单位： | 1. 地质过程与矿产资源国家重点实验室,中国地质大学地球科学与资源学院,北京,100083
2. 地质过程与矿产资源国家重点实验室,中国地质大学地球科学与资源学院,北京,100083;石家庄经济学院资源学院,石家庄,050031 |
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| 基金项目： | 国家自然科学基金重点项目(40830317)、国家“973”规划项目(2009CB421002)、教育部新世纪优秀人才支持计划(NCET-10-0711)、111计划（B07011）、国家自然科学基金项目(40973026，40873023)和中国地质调查局综合研究项目(1212010610104) |
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| 摘 要： | 前人对西藏冈底斯中北部白垩纪岩浆岩的岩石成因和地球动力学背景仍然存在很多解释。本文报道了位于北冈底斯(拉萨地块北部)东段巴尔达地区的岩浆岩锆石U-Pb定年、元素地球化学和Sr-Nd-Hf同位素数据,以对这一问题进行约束。巴尔达岩浆岩包括花岗闪长斑岩和安山玢岩。锆石U-Pb定年结果表明,巴尔达岩浆岩侵位于～114Ma,是北冈底斯早白垩世岩浆岩的典型代表之一。巴尔达岩浆岩两种岩石均为高钾钙碱性系列,其中花岗闪长斑岩的SiO2为64.45%～67.52%,全碱(K2O+Na2O)含量为6.23%～7.47%,铝饱和指数(A/CNK)为0.98～1.22,为兼具I型特点的S型花岗岩;安山玢岩SiO2为57.50%～62.15%,K2O含量为2.30%～3.60%,MgO含量为2.27%～4.40%。两种岩石均富集大离子亲石元素和Pb,亏损高场强元素和Ba等。与冈底斯成熟大陆地壳相比,巴尔达岩浆岩具有更高的εNd(t)值(-7.8～-6.8)和相对低的(87Sr/86Sr)t值(0.7094～0.7105),并且具有不均一的锆石εHf(t)值(-4.2～+3.3)和相对年轻的Hf模式年龄(639～975Ma)。锆石Hf同位素数据和锆石饱和温度(768～818℃)均显示幔源物质在巴尔达岩浆岩形成过程中发挥了重要作用。巴尔达岩浆岩可能是在南向俯冲的班公湖-怒江洋岩石圈断离背景下,由上涌的软流圈提供热量诱发岩石圈地幔熔融产生幔源基性熔体侵位到上部地壳,并引发周围酸性物质的熔融混合,混合过程中幔源组分的输入使S型熔体向I型熔体转化。
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| 关 键 词： | 西藏北冈底斯 巴尔达 花岗闪长斑岩 S型花岗岩 安山玢岩 岩浆混合 锆石U-Pb年龄 Sr-Nd-Hf同位素 |
| 收稿时间： | 4/2/2010 12:00:00 AM |
| 修稿时间： | 2010/5/18 0:00:00 |
Petrogenesis of magmatism in the Baerda region of Northern Gangdese, Tibet: Constraints from geochemistry, geochronology and Sr-Nd-Hf isotopes |
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| ZHANG LiangLiang,ZHU DiCheng,ZHAO ZhiDan,DONG GuoChen,MO XuanXue,GUAN Qi,LIU Min and LIU MeiHua.Petrogenesis of magmatism in the Baerda region of Northern Gangdese, Tibet: Constraints from geochemistry, geochronology and Sr-Nd-Hf isotopes[J].Acta Petrologica Sinica,2010,26(6):1871-1888. |
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| Authors: | ZHANG LiangLiang ZHU DiCheng ZHAO ZhiDan DONG GuoChen MO XuanXue GUAN Qi LIU Min and LIU MeiHua |
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| Institution: | State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences,Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences,Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences,Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences,Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences,Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences,Beijing 100083, China; College of Resources, Shijiazhuang University of Economics, Shijiazhuang 050031, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences,Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences,Beijing 100083, China |
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| Abstract: | |
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| Keywords: | Northern Gangdese Tibet Baerda Granodiorite porphyry S-type granite Andesite porphyrite magma mixing Zircon U-Pb dating Sr-Nd-Hf isotope |
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