| 西藏北冈底斯巴木错安山岩的年代学、地球化学及岩石成因 |
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| 引用本文： | 陈越,朱弟成,赵志丹,张亮亮,刘敏,于枫,管琪,莫宣学.西藏北冈底斯巴木错安山岩的年代学、地球化学及岩石成因[J].岩石学报,2010,26(7):2193-2206. |
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| 作者姓名： | 陈越 朱弟成 赵志丹 张亮亮 刘敏 于枫 管琪 莫宣学 |
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| 作者单位： | 1. 中国地质大学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. 中国地质大学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： | 教育部新世纪优秀人才项目( NCET-10-0711)、国家自然科学重点基金(40830317)、国家“973”项目(2009CB427002)、111计划（B07011）和中国地质调查局综合研究项目( 1212010610104) |
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| 摘 要： | 青藏高原南部的冈底斯带中北部地区广泛分布着中生代火山岩及相关侵入岩。由于缺少可靠的年代学和高质量的地球化学数据,使得其成因及地球动力学背景长期以来存在较大争议。为探讨这一问题,本文报道了出露于北冈底斯巴木错东岸安山岩的锆石U-Pb定年、地球化学和Sr-Nd-Hf同位素数据。巴木错安山岩锆石U-Pb年龄为122.1±0.9Ma。岩石为斑状结构,斑晶为斜长石、角闪石和少量辉石、黑云母。岩石SiO2为58.65%～60.16%,全碱(Na2O+K2O)含量为(5.25%～5.52%,平均5.38%),K2O含量为2.67%～2.81%之间,K2O/Na2O均1,TiO2含量较低(0.61%～0.72%),MgO含量为2.78%～3.10%,Mg#值为45～48。岩石相对富集Rb、Th、U、Pb,亏损Ba、Nb、Ta和Ti等元素,显示出弧特征。样品具有较冈底斯成熟大陆地壳(如宁中早侏罗世强过铝质花岗岩)低的(87Sr/86Sr)t(0.7102～0.7103)和高的εNd(t)(-9.3～-9.8)值,Nd同位素单阶段模式年龄为1.61～1.76Ga;锆石εHf(t)值为-4.6～-0.3,地幔模式年龄tDM为795～965Ma。综合岩石学和地球化学研究表明,巴木错安山岩为高钾钙碱性系列,产于大陆岛弧向同碰撞转换的构造环境。该安山岩可能是班公湖-怒江洋向南俯冲于冈底斯带之下的洋壳在重力拖拉下发生板片回转,导致软流圈物质上升提供热量,从而诱发受到俯冲流体改造的古老岩石圈地幔部分熔融并与壳源酸性熔体混合而成的产物。
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| 关 键 词： | 锆石U-Pb年代学 地球化学 岩石成因 巴木错安山岩 西藏冈底斯 |
| 收稿时间： | 2010/5/28 0:00:00 |
| 修稿时间： | 2010/6/28 0:00:00 |
Geochronology, geochemistry and petrogenesis of the Bamco andesites from the northern Gangdese, Tibet |
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| CHEN Yue,ZHU DiCheng,ZHAO ZhiDan,ZHANG LiangLiang,LIU Min,YU Feng,GUAN Qi and MO XuanXue.Geochronology, geochemistry and petrogenesis of the Bamco andesites from the northern Gangdese, Tibet[J].Acta Petrologica Sinica,2010,26(7):2193-2206. |
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| Authors: | CHEN Yue ZHU DiCheng ZHAO ZhiDan ZHANG LiangLiang LIU Min YU Feng GUAN Qi and MO XuanXue |
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| Institution: | State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Science 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, China University of Geosciences, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China |
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| Abstract: | |
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| Keywords: | Zircon U-Pb geochronology Geochemistry Petrogenesis Bamco andesites Northern Gangdese Tibet |
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