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| 青藏高原Pb同位素地球化学及其意义 | |
| 引用本文： | 赵志丹,莫宣学,董国臣,周肃,朱弟成,廖忠礼,孙晨光.青藏高原Pb同位素地球化学及其意义[J].现代地质,2007,21(2):265-274. |
| 作者姓名： | 赵志丹 莫宣学 董国臣 周肃 朱弟成 廖忠礼 孙晨光 |
| 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,北京100083;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,北京100083;中国地质大学,地学实验中心,北京100083 3. 成都地质矿产研究所,四川,成都610082 |
| 基金项目： | 国家重点基础研究发展计划(973计划);国家自然科学基金;中国地质调查局研究项目;高等学校学科创新引智计划;中国科学院重点实验室基金 |
| 摘 要： | 根据青藏高原不同构造单元基底片麻岩、花岗岩类和火山岩等不同类型岩石的486套Pb同位素数据的整理和分析,发现青藏高原岩石圈存在3种主要类型,即亏损Pb同位素的特提斯洋地幔域端元、富集Pb同位素的喜马拉雅成熟大陆地壳端元和青藏高原北部的过渡型Pb同位素的地幔端元。这3类地球化学端元与前人通过Sr-Nd同位素研究获得的3类端元一致。拉萨地块内部不同类型岩石的Pb同位素地球化学特征指示出两类岩浆作用,一类是特提斯洋岩石圈俯冲消减再循环和亏损地幔物质注入导致的亲特提斯洋型岩浆作用,另一类是与类似于喜马拉雅大陆地壳物质加入导致的富集地幔源区有关的超钾质岩浆作用。岩浆作用的Pb同位素地球化学记录了特提斯洋俯冲消减作用和随后发生的印度大陆向北拼合、碰撞和俯冲过程,也记录了大规模的壳幔相互作用对高原岩石圈演化与隆升的贡献。 |
| 关 键 词： | Pb同位素 地球化学 花岗岩 火山岩 青藏高原 |
| 文章编号： | 1000-8527（2007）02-0265-10 |
| 收稿时间： | 2007-04-08 |
| 修稿时间： | 2007-04-082007-05-09 |
Pb Isotopic Geochemistry of Tibetan Plateau and Its Implications |
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| ZHAO Zhi-dan,MO Xuan-xue,DONG Guo-chen,ZHOU Su,ZHU Di-cheng,LIAO Zhong-li,SUN Chen-guang.Pb Isotopic Geochemistry of Tibetan Plateau and Its Implications[J].Geoscience——Journal of Graduate School,China University of Geosciences,2007,21(2):265-274. | |
| Authors: | ZHAO Zhi-dan MO Xuan-xue DONG Guo-chen ZHOU Su ZHU Di-cheng LIAO Zhong-li SUN Chen-guang |
| Institution: | 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Belting 100083, China; 2. School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China; 3. Geological Analysis Center, China University of Geosciences, Beijing 100083, China; 4. Chengdu Institute of Geology and Mineral Resources, Chengdu, Sichuan 610082, China |
| Abstract: | Pb isotopic compositions of basement,granitoids and volcanic rocks in Tibetan Plateau,with a total data sets of 486,were compiled and analyzed.Three different types of main geochemical crustal or mantle geochemical end-members were identified by their Pb characteristics.The first one is the Neo-Tethyan mantle reservoir represented by Yarlung Zangpo ophiolite,showing low Pb features;the second one is the Himalayan continental crust represented by the basement and granitoids from Tethyan and Higher Himalayas with the most enriched Pb compositions;the third one is the North Tibetan Plateau enriched mantle source region,with a medium enriched Pb compositions.These three end-members classification is very consistent with the former result by Sr-Nd isotopic studies.A detailed discrimination for the rocks from Lhasa block allowed us to separate them into two groups.The first group,including the I-type Gangdese granitoid plutons,Linzizong volcanic rocks and adakitic ore-bearing porphyries,etc.,shows strong Tethyan oceanic crust affinity,with significant source contribution of the recycled Tethyan oceanic crust or depleted mantle.The second group,solely represented by the ultrapotassic volcanics found in western Lhasa block,exhibits an obvious input of the Himalayan continental crust to their mantle source regions.In Lhasa block,the main processes of Tethyan subduction and thereafter India-Asia collision were all recorded by Pb isotopic geochemistry in magmatism during different stages.The crust-mantle interaction among the above end-members has played an important role in the evolution and uplift of the Tibetan Plateau. |
| Keywords: | Pb isotope geochemistry granitoid volcanic rocks Tibetan Plateau |
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