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| Neoproterozoic tectonic transition from subduction to back-arc extension along the western Yangtze Block, South China: Petrological evidence of Nb-enriched basalts and arc-type intrusive rocks | |
| Zhu, Yu1; Lai, Shao-Cong1; Xie, Wan-li1; Qin, Jiang-feng1; Zhu, Ren-zhi1; Zhao, Shao-wei2; Liu, Min1; Zhang, Fang-yi1,3; Zhang, Ze-Zhong1,4; Yang, Hang1 | |
| 2023-10-01 | |
| 发表期刊 | GONDWANA RESEARCH
 |
| ISSN | 1342-937X |
| 卷号 | 122页码:163-180 |
| 通讯作者 | Lai, Shao-Cong([email protected]) |
| 摘要 | Identifying the tectonic transition process from persistent slab subduction to back-arc extension is vital for the systematical study of arc magmatic evolution in a temporal perspective. Although Neoproterozoic subduction setting along the western Yangtze Block has been widely documented, the detailed tectonic transition from subduction to back-arc extension was not systematically constrained. The coexistence of Nb-enriched rocks and normal arc-type rocks can generally provide unique insights into back-arc exten-sion background under subduction setting. Herein we therefore present combined data of petrology, min-eralogy, zircon U-Pb geochronology, whole-rock major and trace elements, and Sr-Nd isotopes as well as zircon Lu-Hf isotopes for the Neoproterozoic Nb-enriched basalts and arc-type intrusive rocks (i.e., gab-bros and diorites) from the Luding area along the western Yangtze Block (South China), to characterize back-arc extension setting of Neoproterozoic continental magmatic arc. Zircon U-Pb ages suggest that the Nb-enriched basalts and arc-type gabbros-diorites formed coevally at ca. 780 Ma. The Nb-enriched basalts have much clinopyroxene phases and display higher TiO2, P2O5, Nb, Nb/La, and Nb/U values than normal arc volcanics. They are weakly enriched in Rb and Ba, and slightly depleted in Nb, Ta, Zr, and Hf, and show decoupled Nd-Hf isotopes with highly positive whole-rocks ENd(t) (+5.79 ti +7.39) and rela-tively low zircon EHf(t) (+1.09 ti +9.05) values, indicating an origination of subduction slab melts-metasomatized mantle wedge source, resembling with the genesis of those typical Nb-enriched mafic rocks in a back-arc setting. Compared with Nb-enriched basalts, the arc-type gabbros and diorites contain more hornblende minerals, and are characterized by variably high MgO (3.10-5.71 wt%) contents and Mg# values (51.5-57.2), and enriched LREEs and LILEs (e.g., Rb, Ba, Sr, and K) as well as depleted Nb, Ta, and Ti. Considering their relatively depleted and coupled Nd-Hf isotopes, these arc-type gabbros and diorites were formed by partial melting of hydrous mantle wedge modified by subduction fluids. The co-occurrence of Nb-enriched basalts and arc-type gabbros-diorites studied here therefore reveal Neoproterozoic back-arc extension background under the subduction setting. Combined with ca. 810- 780 Ma mafic rocks showing Nb-enriched signatures and ca. 860-740 Ma normal arc-type mafic-intermediate rocks in the western Yangtze Block, we support that Neoproterozoic geodynamic transition from continuing subduction to back-arc extension initially occurred at ca. 820-810 Ma. The Neoproterozoic back-arc extension is thus significant for geochemical changes of subduction-related metasomatized agents and arc magmatic types. & COPY; 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. |
| 关键词 | Nb-enriched basalt Arc-type gabbros and diorites Western Yangtze Block Neoproterozoic Subduction-related back-arc extension |
| DOI | 10.1016/j.gr.2023.05.024 |
| 收录类别 | SCI |
| 语种 | 英语 |
| 资助项目 | National Natural Science Foun-dation of China[42202048]; National Natural Science Foun-dation of China[42172056]; China Postdoctoral ScienceFoundation[2021M702647] |
| WOS研究方向 | Geology |
| WOS类目 | Geosciences, Multidisciplinary |
| WOS记录号 | WOS:001032656400001 |
| 出版者 | ELSEVIER |
| WOS关键词 | STRENGTH ELEMENT ENRICHMENT ; SLAB-DERIVED MELTS ; I-TYPE GRANITES ; A-TYPE GRANITES ; SW CHINA ; SICHUAN PROVINCE ; VOLCANIC-ROCKS ; HF ISOTOPES ; CONTINENTAL-CRUST ; MAFIC INTRUSIONS |
| 引用统计 | |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://ir.qdio.ac.cn/handle/337002/182572 |
| 专题 | 深海极端环境与生命过程研究中心 |
| 通讯作者 | Lai, Shao-Cong |
| 作者单位 | 1.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China 2.Changan Univ, Sch Earth Sci & Resources, Key Lab Western Chinas Mineral Resources & Geol En, Minist Educ, Xian 710054, Peoples R China 3.Chinese Acad Sci, Inst Oceanol, Ctr Deep Sea Res, Ctr Ocean Mega Sci, Qingdao 266071, Peoples R China 4.Design & Res Inst Co Ltd, China Three Gorges Corp, Shanghai Invest, Shanghai 200335, Peoples R China |
| 推荐引用方式 GB/T 7714 | Zhu, Yu,Lai, Shao-Cong,Xie, Wan-li,et al. Neoproterozoic tectonic transition from subduction to back-arc extension along the western Yangtze Block, South China: Petrological evidence of Nb-enriched basalts and arc-type intrusive rocks[J]. GONDWANA RESEARCH,2023,122:163-180. |
| APA | Zhu, Yu.,Lai, Shao-Cong.,Xie, Wan-li.,Qin, Jiang-feng.,Zhu, Ren-zhi.,...&Yang, Hang.(2023).Neoproterozoic tectonic transition from subduction to back-arc extension along the western Yangtze Block, South China: Petrological evidence of Nb-enriched basalts and arc-type intrusive rocks.GONDWANA RESEARCH,122,163-180. |
| MLA | Zhu, Yu,et al."Neoproterozoic tectonic transition from subduction to back-arc extension along the western Yangtze Block, South China: Petrological evidence of Nb-enriched basalts and arc-type intrusive rocks".GONDWANA RESEARCH 122(2023):163-180. |
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