Decoupling of isotopes between magmatic zircons and their mafic host rocks: A case study from the ca. 830 Ma Jiabang dolerite, South China
文献类型：期刊论文
| 作者 | Wu, Tao1,2,3; Wang, Xuan-Ce3,4; Wilde, Simon A.5; Li, Qiu-Li6; Pang, Chong-Jin7; Zhou, Jia-Xi3 |
| 刊名 | PRECAMBRIAN RESEARCH
 |
| 出版日期 | 2022-02-01 |
| 卷号 | 369页码:12 |
| ISSN号 | 0301-9268 |
| 关键词 | Zircon Hf-O isotopes Whole-rock Nd-Hf isotopes Isotope decoupling Crustal contamination South China |
| DOI | 10.1016/j.precamres.2021.106519 |
| 英文摘要 | Zircon is widely used to constrain the crystallization age and magma source of the host rocks. However, in recent years an increasing number of studies have demonstrated that Hf-O isotopes of zircon grains are not always in equilibrium with the whole-rock isotopes of the host rocks. Here we present a case from the Jiabang dolerite from southeastern Guizhou Province, South China, to demonstrate the decoupling of isotopes between magmatic zircons and their mafic host rocks as a result of limited crustal contamination. In-situ SIMS U-Pb zircon dating shows that the Jiabang dolerite formed at 838 & nbsp;+/- 7 Ma. The Jiabang dolerite has low SiO2 of 47.6 - 54.2 wt%, high MgO of 4.93 - 15.6 wt%, and Fe(2)O(3 )of 8.51 - 11.9 wt%, typical of mantle-derived magma. All whole-rock samples in this study have depleted Nd-Hf isotopes, with epsilon(Nd)(t) values ranging from + 2.6 to + 3.8 and epsilon(Hf()t) values from + 6 to + 10, with whole-rock epsilon(Nd)(t) values similar to those of contemporary OIB-like mantle-derived melts in South China. Such whole-rock chemical features imply that the source of the Jiabang dolerites is mantle-dominated and that any crustal contribution should be insignificant. However, zircons from the dolerite display negative epsilon(Hf)(t) values of-6 to-1 and high delta 18O values of 9.7-11.5 & nbsp;parts per thousand & nbsp; that are similar to those of the Guibei granitoids in the study area, suggesting a crustal origin. Our AFC simulation based on Magma Chamber Simulator (MCS) demonstrates that AFC played a limited role in the generation of the Jiabang dolerite and indicates that the decoupling between zircon Hf-O and the whole-rock Nd-Hf isotopes likely reflects a contribution from wallrock-derived melts during emplacement of the dolerites. We propose that the zircons crystallized in inter-stitial liquids that were contaminated by crustal-derived fluids/melts, resulting in decoupling between the whole-rock isotopes and the magmatic zircon isotopes. Due to mass balance requirements, the crustal melts/fluids would have insignificant effect on the whole-rock isotopes, but will strongly modify the Hf-O isotopes of zircons that crystallized in the interstitial liquids. This case study shows that caution needs to be applied when comparing zircon Hf-O isotopes from mafic intrusive rocks to constrain their source. |
| WOS关键词 | BIMODAL VOLCANIC-ROCKS ; U-PB AGE ; YIDUN ARC BELT ; YANGTZE BLOCK ; OXYGEN ISOTOPES ; PERALUMINOUS GRANITOIDS ; GEOCHEMICAL EVIDENCE ; NORTHERN YANGTZE ; WESTERN MARGIN ; MANTLE SOURCE |
| 资助项目 | National Natural Science Foundation of China[42072069] ; Research Start-up Project for Introduced Talent of Yunnan University[20190043] ; Funda-mental Research Key Project of Yunnan Province[202001BB050015] |
| WOS研究方向 | Geology |
| 语种 | 英语 |
| 出版者 | ELSEVIER |
| WOS记录号 | WOS:000783921400001 |
| 资助机构 | National Natural Science Foundation of China ; National Natural Science Foundation of China ; Research Start-up Project for Introduced Talent of Yunnan University ; Research Start-up Project for Introduced Talent of Yunnan University ; Funda-mental Research Key Project of Yunnan Province ; Funda-mental Research Key Project of Yunnan Province ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Research Start-up Project for Introduced Talent of Yunnan University ; Research Start-up Project for Introduced Talent of Yunnan University ; Funda-mental Research Key Project of Yunnan Province ; Funda-mental Research Key Project of Yunnan Province ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Research Start-up Project for Introduced Talent of Yunnan University ; Research Start-up Project for Introduced Talent of Yunnan University ; Funda-mental Research Key Project of Yunnan Province ; Funda-mental Research Key Project of Yunnan Province ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; Research Start-up Project for Introduced Talent of Yunnan University ; Research Start-up Project for Introduced Talent of Yunnan University ; Funda-mental Research Key Project of Yunnan Province ; Funda-mental Research Key Project of Yunnan Province |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/105102]  |
| 专题 | 地质与地球物理研究所_岩石圈演化国家重点实验室 |
| 通讯作者 | Wang, Xuan-Ce |
| 作者单位 | 1.Zhejiang Univ, Ocean Coll, 1 Zheda Rd, Zhoushan 316021, Peoples R China 2.Zhejiang Univ, Hainan Inst, Bldg 11,Yonyou Ind Pk, Sanya 572025, Hainan, Peoples R China 3.Yunnan Univ, Sch Earth Sci, Kunming 650500, Yunnan, Peoples R China 4.Univ Queensland, Sch Earth & Environm Sci, Radiogen Isotope Facil, Brisbane, Qld 4072, Australia 5.Curtin Univ, Sch Earth & Planetary Sci, Inst Geosci Res, GPO Box U1987, Perth, WA 6845, Australia 6.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China 7.Guilin Univ Technol, Guangxi Key Lab Hidden Metall Ore Deposits Explor, Guilin 541004, Guangxi, Peoples R China |
| 推荐引用方式 GB/T 7714 | Wu, Tao,Wang, Xuan-Ce,Wilde, Simon A.,et al. Decoupling of isotopes between magmatic zircons and their mafic host rocks: A case study from the ca. 830 Ma Jiabang dolerite, South China[J]. PRECAMBRIAN RESEARCH,2022,369:12. |
| APA | Wu, Tao,Wang, Xuan-Ce,Wilde, Simon A.,Li, Qiu-Li,Pang, Chong-Jin,&Zhou, Jia-Xi.(2022).Decoupling of isotopes between magmatic zircons and their mafic host rocks: A case study from the ca. 830 Ma Jiabang dolerite, South China.PRECAMBRIAN RESEARCH,369,12. |
| MLA | Wu, Tao,et al."Decoupling of isotopes between magmatic zircons and their mafic host rocks: A case study from the ca. 830 Ma Jiabang dolerite, South China".PRECAMBRIAN RESEARCH 369(2022):12. |
入库方式： OAI收割
来源：地质与地球物理研究所
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