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Decoupling of isotopes between magmatic zircons and their mafic host rocks: A case study from the ca. 830 Ma Jiabang dolerite, South China
Wu, Tao1,2,3; Wang, Xuan-Ce3,4; Wilde, Simon A.5; Li, Qiu-Li6; Pang, Chong-Jin7; Zhou, Jia-Xi3
2022-02-01
Source PublicationPRECAMBRIAN RESEARCH
ISSN0301-9268
Volume369Pages:12
AbstractZircon 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.
KeywordZircon Hf-O isotopes Whole-rock Nd-Hf isotopes Isotope decoupling Crustal contamination South China
DOI10.1016/j.precamres.2021.106519
Funding OrganizationNational 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
WOS KeywordBIMODAL VOLCANIC-ROCKS ; U-PB AGE ; YIDUN ARC BELT ; YANGTZE BLOCK ; OXYGEN ISOTOPES ; PERALUMINOUS GRANITOIDS ; GEOCHEMICAL EVIDENCE ; NORTHERN YANGTZE ; WESTERN MARGIN ; MANTLE SOURCE
Language英语
Funding ProjectNational 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]
Funding OrganizationNational 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
WOS Research AreaGeology
WOS SubjectGeosciences, Multidisciplinary
WOS IDWOS:000783921400001
PublisherELSEVIER
Citation statistics
Document Type期刊论文
Identifierhttp://ir.iggcas.ac.cn/handle/132A11/105102
Collection岩石圈演化国家重点实验室
Corresponding AuthorWang, Xuan-Ce
Affiliation1.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
Recommended Citation
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.
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