| 西藏申扎早白垩世花岗岩类:板片断离的证据 |
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| 引用本文： | 张亮亮,朱弟成,赵志丹,廖忠礼,王立全,莫宣学.西藏申扎早白垩世花岗岩类:板片断离的证据[J].岩石学报,2011,27(7):1938-1948. |
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| 作者姓名： | 张亮亮 朱弟成 赵志丹 廖忠礼 王立全 莫宣学 |
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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. 成都地质矿产研究所,成都,610082 |
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| 基金项目： | 本文受中央高校基本科研业务费专项资金项目(2010ZD02)、教育部新世纪优秀人才项目(NCET-10-0711)、国家973项目(2011CB403102、2009CB421002)、国家自然科学重点基金项目(40830317)、国土资源部百名优秀青年科技人才计划项目(200702)、国家自然科学基金面上项目(40973062、40873023)和中国地质调查局综合研究项目(1212010610104)联合资助. |
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| 摘 要： | 拉萨地块中北部地区在~113Ma发生的带状岩浆大爆发事件被认为是南向俯冲的班公湖-怒江洋壳岩石圈板片断离的结果,但缺乏更多的地球化学数据。本文报道的拉萨地块中部申扎地区花岗岩类地球化学数据为这一模型提供了可靠的地球化学证据。申扎花岗岩类包括寄主花岗闪长岩(113Ma),辉长质包体和闪长质包体(111Ma)。申扎早白垩世花岗岩中的寄主岩石与镁铁质包体均属于偏铝质中-高钾钙碱性系列,所有样品均富集大离子亲石元素(如Rb、Ba、U和Th)、亏损高场强元素(如Nb、Ta、Ti和Zr)。花岗闪长质寄主岩和闪长质包体具有高的(87Sr/86Sr)i值(0.7121~0.7133),负的εNd(t)值(-10.2~-9.1)及古老的Nd同位素模式年龄(1.90~1.55Ga);辉长质包体具偏低的(87Sr/86Sr)i值(0.7067和0.7108),较高的全岩εNd(t)(-2.1和-4.1)值,Nd同位素模式年龄为1.33Ga和1.32Ga。申扎花岗岩类中的辉长质包体具有板内玄武岩亲缘性,这一特征与班公湖-怒江洋壳岩石圈南向俯冲板片在~113Ma左右发生的板片断离有关。申扎花岗岩类是在板片断离背景下,主要由来源于古老拉萨基底物质重熔的熔体与上涌的软流圈地幔物质发生岩浆混合产生的。
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| 关 键 词： | 拉萨地块 申扎 花岗闪长岩 辉长质包体 闪长质包体 岩浆混合 板片断离 |
| 收稿时间： | 4/1/2011 12:00:00 AM |
| 修稿时间： | 2011/5/28 0:00:00 |
Early Cretaceous granitoids in Xainza, Tibet: Evidence of slab break-off |
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| ZHANG LiangLiang,ZHU DiCheng,ZHAO ZhiDan,LIAO ZhongLi,WANG LiQuan and MO XuanXue.Early Cretaceous granitoids in Xainza, Tibet: Evidence of slab break-off[J].Acta Petrologica Sinica,2011,27(7):1938-1948. |
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| Authors: | ZHANG LiangLiang ZHU DiCheng ZHAO ZhiDan LIAO ZhongLi WANG LiQuan and MO XuanXue |
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| Institution: | State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;Chengdu Institute of Geology and Mineral Resources, Chengdu, 610082, China;Chengdu Institute of Geology and Mineral Resources, Chengdu, 610082, China;State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China |
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| Abstract: | The magmatic flare-up at ~113Ma occurred in the central and northern Lhasa Terrane has been attributed to the slab break-off of the southward subduction of the Bangong-Nujiang Ocean seafloor, but the bulk-rock geochemical data are limited. Bulk-rock data, including major element, trace element, and Sr-Nd isotopic data of the granitoids from Xainza in the central Lhasa Subterrane, Tibet, reported in this paper provide reliable geochemical lines of evidence for this model. The granitoids from Xainza include g... |
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| Keywords: | Lhasa Terrane Xainza Granodiorite Gabbroic enclaves Dioritic enclaves Magma mixing Slab break-off |
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