| 甘肃敦煌水峡口地区前寒武纪岩石的锆石U-Pb年龄、Hf同位素组成及其地质意义 |
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| 引用本文： | 赵燕,第五春荣,孙勇,朱涛,王洪亮.甘肃敦煌水峡口地区前寒武纪岩石的锆石U-Pb年龄、Hf同位素组成及其地质意义[J].岩石学报,2013,29(5):1698-1712. |
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| 作者姓名： | 赵燕 第五春荣 孙勇 朱涛 王洪亮 |
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| 作者单位： | 1. 大陆动力学国家重点实验室,西北大学地质学系,西安 710069
2. 中国地质调查局西安地质调查中心,西安,710054 |
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| 基金项目： | 本文受中国地质调查局项目(1212011121137);国家自然科学基金项目(41272004)和西北大学大陆动力学国家重点实验室科技部专项联合资助. |
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| 摘 要： | 敦煌杂岩位于塔里木克拉通的东部,探寻和研究其中的早前寒武纪地质体对于探讨敦煌地块早前寒武纪地壳的形成和演化及其构造归属等问题具有重要的意义.甘肃敦煌水峡口地区的敦煌杂岩主要由英云闪长质片麻岩、花岗闪长质片麻岩以及表壳岩石组成.利用LA-ICP-MS锆石U-Pb定年方法测得水峡口英云闪长片麻岩和花岗片麻岩原岩的形成年龄分别为2561±16Ma和2510±22Ma,确证了在敦煌杂岩中存在太古宙岩石.此外,还获得斜长角闪岩的变质年龄为1806±14Ma,推测其原岩岩浆可能来自古老岩石圈地幔的部分熔融.根据已有的资料提出在古元古代晚期(1.80 ～ 1.85Ga)敦煌杂岩经历了一期较广泛的变质作用.锆石Hf同位素显示～2.5Ga的岩石年龄在敦煌地块代表新太古代晚期重要地壳生长时期,而～1.8Ga的构造-热事件则是以古老地壳物质循环再造为主.这些资料显示敦煌地块和华北克拉通在早前寒武纪经历了类似的地壳形成和演化过程,且共同记录了全球性的Columbia碰撞造山事件信息.
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| 关 键 词： | 敦煌地块 敦煌杂岩 地壳生长 锆石 Hf同位素 |
| 收稿时间： | 2/1/2013 12:00:00 AM |
| 修稿时间： | 2013/4/15 0:00:00 |
Zircon geochronology and Lu-Hf isotope compositions for Precambrian rocks of the Dunhuang complex in Shuixiakou area, Gansu Province |
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| ZHAO Yan,DIWU ChunRong,SUN Yong,ZHU Tao and WANG HongLiang.Zircon geochronology and Lu-Hf isotope compositions for Precambrian rocks of the Dunhuang complex in Shuixiakou area, Gansu Province[J].Acta Petrologica Sinica,2013,29(5):1698-1712. |
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| Authors: | ZHAO Yan DIWU ChunRong SUN Yong ZHU Tao and WANG HongLiang |
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| Institution: | State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China;State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China;State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China;Xi'an Center of Geological Survey, CGS, Xi'an 710054, China;Xi'an Center of Geological Survey, CGS, Xi'an 710054, China |
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| Abstract: | Dunhuang block is located in the southeast of Tarim Craton, and the research of Precambrian Dunhuang complex is of great significance in investigating the formation and evolution of the crust of Dunhuang block, as well as its tectonic relationship with the North China Craton and Yangtze Craton. Dunhuang complex, in Shuixiakou area, Gansu Province, mainly consists of tonalitic-granodioritic gneisses, granitic gneisses and metamorphosed supracrustal rocks. The age of 2561±16Ma and 2510±22Ma respectively for the tonalitic and the granitic gneisses by LA-ICP-MS U-Pb dating of zircons confirm the existence of Archean rocks in Dunhuang complex, LA-ICP-MS U-Pb dating of zircons yielded a metamorphic age of 1806±14Ma for the amphibolite, and its parent magma probably derived from the partial melting of ancient lithospheric mantle. Based on the integration of our study and the available data, we put forward that Dunhuang complex has experienced a metamorphism during the Late Paleoproterozoic (1.80~1.85Ga). The analysis of Hf isotopes of zircons indicates that ~2.5Ga is a major period of crustal growth in Dunhuang block during the Neoarchean, while the ~1.8Ga tectonic-thermal event represent a reworking period of ancient crust. The above data show that the formation and evolution of Dunhuang block is similar with the North China Craton during Early Precambrian, and they are involved in the global collision-orogenic event during Columbia Period. |
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| Keywords: | Dunhuang block Dunhuang complex Crustal growth Zircon Hf isotope composition |
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