Preliminary study on the components of the lower crust in east China Plateau during Yanshanian Period: Constraints on Sr and Nd isotopic compositions of adakite-like rocks.
文献类型：期刊论文
| 作者 | Zhang, Q; Wang, Y; Wang, YL |
| 刊名 | ACTA PETROLOGICA SINICA
 |
| 出版日期 | 2001-10-01 |
| 卷号 | 17期号:4页码:505-513 |
| 关键词 | Yanshan Period East China Plateau composition of the lower crust adakite-like rocks Sr-Nd isotopic composition |
| ISSN号 | 1000-0569 |
| 文献子类 | Article |
| 英文摘要 | The composition of continental crust has always been an interesting subject for many geologists. However, the big difficulty is how to determine the composition of the deep crust, especially the composition of the lower crust. The identification of adakite-like rocks within the continental crust may provide a possible way to make sense of the problem. The geochemical characteristics of C-type adakite-like rocks in the eastern China show that they are the products of partial melting of intermediate to mafic granulites in the deep lower crust in high P-T condition, the composition of the lower crust therefore can be traced by these adakite-like rocks. Our preliminary studies show that the geochemical characteristics of adakite-like rocks are different from place to place in the eastern China, suggesting that the lower crust sources from which the adakite-like rocks are derived varying in the compositions from place to place too. Based on the Sr-Nd isotopic compositions of these adakite-like rocks, the lower crust of east China Plateau is argued to be formed by three different parts of Jiaodong-Dabei district, Beijing-Liaoxi district and the lower Yangtze district (the middle-lower reaches of Yangtze River). Following opinions are discussed in the paper. (1) The lower crust of Jiaodong area is characteristic of high SiO2 content, low Na2O/K2O ratios (0.8 similar to1.3), high I-Sr ratios (0.709 similar to0.712), low epsilon (Nd)(t) values (-15 similar to -21) and high T-DM ages (1.9 similar to2.1Ga), whereas the lower crust of Dabie area has relatively low Is, ratios, which is the upper Is, ratio limit of the whole area and may probably represent the composition of Mesozoic basement. (2) The lower Yangtze district lies in the Yangtze Block, in which Mesozoic adakite-like rocks have variable I-Sr ratios, epsilon (Nd) (t) values and T-DM ages, suggesting the underplating of abundant young basaltic magma beneath the lower crust basement of Proterozoic. The adakite-like rocks from Tongling area have relatively high Is. ratios (0.707 similar to0.709), low epsilon (Nd) (t) values (similar to 11 similar to -16) and high T-DM age (1.7-2.2Ga), similar to that of the lower crust of Yangtze basement. (3) The Sr-Nd isotopic compositions of the adakite-like rocks in Liaoxi-Beijing area are characteristic of low I-Sr ratios (0.705 similar to0.707), varying epsilon (Nd)(t) values (-4 similar to -20) and T-DM ages (0.7 similar to2.1Ga), reflecting that the composition of the lower crust in Liaoxi-Beijing area is rather complicated. The Sr-Nd isotopic composition of the adakite-like rocks in Beijing-Zhangwu area is similar to that of granulite inclusions from Hannuoba basalts and far beyond the epsilon (Nd) (t) values ( - 32 similar to - 44) of the lower crust of the North China Block. These adakite-like rocks therefore are assumed not to be derived from the old Archean lower crust of North China Block, but the products of partial melting of young underplating basic granulite of Mesozoic age beneath the lower crust of North China. In addition, the shortcoming of using adakite-like rocks tracing the composition of the lower crust is also discussed in the paper. |
| WOS关键词 | CONTINENTAL-CRUST ; SUBDUCTION ; MAGMAS ; GEOCHEMISTRY ; GRANITOIDS ; ORIGIN |
| WOS研究方向 | Geology |
| 语种 | 英语 |
| WOS记录号 | WOS:000172356500001 |
| 出版者 | SCIENCE PRESS |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/76691]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | Zhang, Q |
| 作者单位 | 1.Chinese Acad Sci, Inst Geol & Geophys, Beijing 10029, Peoples R China 2.NW Univ Xian, Dept Geol, Xian 710069, Peoples R China |
| 推荐引用方式 GB/T 7714 | Zhang, Q,Wang, Y,Wang, YL. Preliminary study on the components of the lower crust in east China Plateau during Yanshanian Period: Constraints on Sr and Nd isotopic compositions of adakite-like rocks.[J]. ACTA PETROLOGICA SINICA,2001,17(4):505-513. |
| APA | Zhang, Q,Wang, Y,&Wang, YL.(2001).Preliminary study on the components of the lower crust in east China Plateau during Yanshanian Period: Constraints on Sr and Nd isotopic compositions of adakite-like rocks..ACTA PETROLOGICA SINICA,17(4),505-513. |
| MLA | Zhang, Q,et al."Preliminary study on the components of the lower crust in east China Plateau during Yanshanian Period: Constraints on Sr and Nd isotopic compositions of adakite-like rocks.".ACTA PETROLOGICA SINICA 17.4(2001):505-513. |
入库方式： OAI收割
来源：地质与地球物理研究所
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