| Zircon U-Pb ages, Hf-O isotopes and whole-rock Sr-Nd-Pb isotopic geochemistry of granitoids in the Jinshajiang suture zone, SW China:Constraints on petrogenesis and tectonic evolution of the Paleo-Tethys Ocean | |
Jing-Jing Zhu; Rui-Zhong Hu ; Xian-Wu Bi; Hong Zhong; Heng Chen
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| 2011 | |
| 发表期刊 | Lithos
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| 卷号 | 126期号:3-4页码:248-264 |
| 摘要 | The Jinshajiang suture zone, located in the eastern part of the Tethyan tectonic domain, is noticeable for a large-scale distribution of Late Jurassic to Triassic granitoids. These granitoids were genetically related to the evolution of the Paleo-Tethys Ocean. Beiwu, Linong and Lunong granitoids occur in the middle zone of the Jinshajiang Suture Zone, and possess similar geochemical features, indicating that they share a common magma source. SIMS zircon U-Pb dating reveals that the Beiwu. Linong and Lunong granitic intrusions were emplaced at 233.9 +/- 1.4 Ma (2 sigma), 233.1 +/- 1.4 Ma (2 sigma) and 231.0 +/- 1.6 Ma (2 sigma), respectively. All of these granitoids are enriched in abundances of Si (SiO(2t)=65.2-73.5 wt.%), and large-ion lithophile elements (LILEs). but depleted in high field strength elements contents (HFSEs, e.g., Nb. Ta, and Ti). In addition, they have low P(2)O(5) contents (0.06-0.11 wt.%), A/CNK values ([molecular Al(2)O(3)/(CaO + Na(2)O + K(2)O)]. mostly <1.1) and 10,000 Ga/Al ratios (1.7-2.2), consistent with the characteristics of I-type granites. In terms of isotopic compositions, these granitoids have high initial (87)Sr/(86)Sr ratios (0.7078-0.7148). Pb isotopic compositions [((206)Pb/(204)Pb)(t) = 18.213-18.598, ((207)Pb/(204)Pb)(t) = 15.637-15.730 and ((208)Pb/(204)Pb)(t) = 38.323-38.791] zircon delta(18)O values (7.3 parts per thousand-9.3 parts per thousand) and negative epsilon(Nd)(t) values (-5.1 to -6.7), suggesting they were predominantly derived from the continental crust. Their Nb/Ta ratios (average value = 8.6) are consistent with those of the lower continental crust (LCC). However, variable epsilon(Hf)(t) values (-8.6 to +2.8) and the occurrences of mafic microgranular enclaves (MMEs) suggest that mantle-derived melts and lower crustal magmas were involved in the generation of these granitoids. Moreover, the high Pb isotopic ratios and elevated zircon delta(18)O values of these rocks indicate a significant contribution of the upper crustal composition. We propose a model in which the Beiwu, Linong and Lunong granitoids were generated under a late collisional or post-collisional setting. It is possible that this collision was completed before Late Triassic. Decompression induced mantle-derived magmas to be underplated and provided the heat for the anatexis of the crust. Hybrid melts including mantle-derived and the lower crustal magmas were then generated. The hybrid melts thereafter ascended to a shallow depth and resulted in some degree of sedimentary rock assimilation. Such three-component mixing magma source and subsequent fractional crystallization could be responsible for the formation of the Beiwu, Linong and Lunong granitoids. |
| 学科领域 | 矿床地球化学 |
| 收录类别 | SCI |
| 语种 | 英语 |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://ir.gyig.ac.cn/handle/352002/4906 |
| 专题 | 矿床地球化学国家重点实验室_矿床地球化学国家重点实验室_期刊论文 矿床地球化学国家重点实验室 |
| 通讯作者 | Rui-Zhong Hu |
| 推荐引用方式 GB/T 7714 | Jing-Jing Zhu,Rui-Zhong Hu,Xian-Wu Bi,et al. Zircon U-Pb ages, Hf-O isotopes and whole-rock Sr-Nd-Pb isotopic geochemistry of granitoids in the Jinshajiang suture zone, SW China:Constraints on petrogenesis and tectonic evolution of the Paleo-Tethys Ocean[J]. Lithos,2011,126(3-4):248-264. |
| APA | Jing-Jing Zhu,Rui-Zhong Hu,Xian-Wu Bi,Hong Zhong,&Heng Chen.(2011).Zircon U-Pb ages, Hf-O isotopes and whole-rock Sr-Nd-Pb isotopic geochemistry of granitoids in the Jinshajiang suture zone, SW China:Constraints on petrogenesis and tectonic evolution of the Paleo-Tethys Ocean.Lithos,126(3-4),248-264. |
| MLA | Jing-Jing Zhu,et al."Zircon U-Pb ages, Hf-O isotopes and whole-rock Sr-Nd-Pb isotopic geochemistry of granitoids in the Jinshajiang suture zone, SW China:Constraints on petrogenesis and tectonic evolution of the Paleo-Tethys Ocean".Lithos 126.3-4(2011):248-264. |
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