Geochemical characteristics and petrogenesis of the two types of Neoarchean gneisses from the Jiaobei terrane
文献类型：期刊论文
| 作者 | Shan HouXiang1,2; Zhai MingGuo1; Wang Fang1; Zhang HuaFeng3 |
| 刊名 | ACTA PETROLOGICA SINICA
 |
| 出版日期 | 2013-07-01 |
| 卷号 | 29期号:7页码:2295-2312 |
| 关键词 | TTG gneisses Garnet biotite plagiogneiss Petrogenesis Jiaobei terrane Neoarchean |
| ISSN号 | 1000-0569 |
| 文献子类 | Article |
| 英文摘要 | Two types of Neoarchean gneisses are identified in the three deep exploration drills in the Jiaobei terrane, including the dominating TTG gneisses and the minor garnet biotite plagiogneiss being sandwiched between the former. As recorded, their protolithes both formed at similar to 2.5Ga. The TTG gneisses are rich in SiO2 (53.95% similar to 75.56%), Al2O3 (most > 15%, 10.45% similar to 17.64%) and Na2O (1.51% similar to 5.94%) with high Na2O/K2O ratios (> 1) and low Fe2O3T (2.22% similar to 9.54%) and MgO (0.53% similar to 4.87%) contents. Their A/CNK ratios (1.18 similar to 1.75) indicate that they belong to high-Al TTG series. The TTG gneisses are rich in LILE (Rb, Ba and Sr) but deplete HFSE (Nb, Ta, Zr and Hf), characterized by high Sr contents (204 x 10(-6) similar to 2906 x 10(-6)) and Sr/Y ratios (7.30 similar to 355), relatively high Sigma REE contents (40.4 x 10(-6) similar to 512 x 10(-6)), strongly fractionated REE patterns ((La/Yb)(N) = 11.5 similar to 121) and positive or no Eu anomalies (delta Eu = 0.79 similar to 1.89). These geochemical features request melting of plagioclase component and relicts of garnet, amphibole and some Ti-bearing minerals in the source, indicating that the TTG were formed by partial melting of hydrous basaltic crust at high pressure. The whole rock Nd and zircon Hf isotopic studies, in which the t(DM) is close to the formation age, indicate that the TTG may originate from a juvenile crust from a depleted mantle at 2.57 similar to 2.64Ga. In addition, their high Mg-# numbers (40 similar to 67) and high Cr (147 x 10(-6) similar to 371 x 10(-6)) and Ni contents (6.68 x 10(-6) similar to 156 x 10(-6)) indicate reaction with mantle wedge. Combining features such as negative Nb, Ta anomalies and the juvenile source, the TTG in this study may have formed in island arc environment related to subduction instead of thickened lower crust. DF values and the K-A diagram show that the protolith of garnet biotite plagiogneiss is pelitic-silty sedimentary rocks. Their Cr/Zr ratios (0.90 similar to 1.99, 1.62 on the average), Th/Sc ratios (0.30 on the average) and REE patterns are similar to the corresponding characteristics (1.44 and 0.4, respectively) of Archean sedimentary rocks, thus indicating their source is mainly composed of quartz-feldspathic material. Most samples are rich in LREE with weak negative or no Eu anomalies (delta Eu = 0.69 similar to 0.92, 0.84 on the average) and have relatively flat HREE patterns. The characteristic values of REE (176 x 10(-6) on average) contents, (La/Yb)(N) (14.7 on average) and LREE/HREE ratios (3.3 on average) indicate that the protolith may probably have formed in island arc environment or active continental margin. Amphibolite facies metamorphism, which is indicated by the peak metamorphic temperature obtained by Grt-Bi thermometer (549 similar to 663 degrees C) and biotite composition, may represent the imprint of retrogressive metamorphic stages of granulite-high amphibolite facies metamorphism at similar to 2.5Ga. The protolith of garnet biotite plagiogneiss and TTG are the products of the same age and similar tectonic settings (island arc environment or active continental margin), suggesting a subduction process in the area at that time. And the metamorphism at similar to 2.5Ga, which is slightly later than the TTG magma event, may be related to the collision process after subduction. |
| WOS关键词 | ZIRCON U-PB ; EARLY CONTINENTAL-CRUST ; NORTH CHINA CRATON ; EXPERIMENTAL CONSTRAINTS ; ARCHEAN TRONDHJEMITES ; METAMORPHIC ROCKS ; SUBDUCTION ZONES ; TTG GENESIS ; GROWTH ; AMPHIBOLITE |
| WOS研究方向 | Geology |
| 语种 | 英语 |
| WOS记录号 | WOS:000322926000003 |
| 出版者 | SCIENCE PRESS |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/87738]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | Shan HouXiang |
| 作者单位 | 1.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China 2.Univ Chinese Acad Sci, Coll Earth Sci, Beijing 100049, Peoples R China 3.China Univ Geosci, Dept Geosci & Resources, Beijing 100083, Peoples R China |
| 推荐引用方式 GB/T 7714 | Shan HouXiang,Zhai MingGuo,Wang Fang,et al. Geochemical characteristics and petrogenesis of the two types of Neoarchean gneisses from the Jiaobei terrane[J]. ACTA PETROLOGICA SINICA,2013,29(7):2295-2312. |
| APA | Shan HouXiang,Zhai MingGuo,Wang Fang,&Zhang HuaFeng.(2013).Geochemical characteristics and petrogenesis of the two types of Neoarchean gneisses from the Jiaobei terrane.ACTA PETROLOGICA SINICA,29(7),2295-2312. |
| MLA | Shan HouXiang,et al."Geochemical characteristics and petrogenesis of the two types of Neoarchean gneisses from the Jiaobei terrane".ACTA PETROLOGICA SINICA 29.7(2013):2295-2312. |
入库方式： OAI收割
来源：地质与地球物理研究所
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