Variations of Sr-Nd-Hf-O isotopes and redox conditions across a Neoproterozoic arc magmatic belt in the western margin of the Yangtze craton

doi:10.1016/j.chemgeo.2023.121735

	Variations of Sr-Nd-Hf-O isotopes and redox conditions across a Neoproterozoic arc magmatic belt in the western margin of the Yangtze craton
	Yao, Junhua 1,2,5; Zhu, Wei-Guang 2; Li, Chusi 2,3; Bai, Zhong-Jie 2; Wang, Yan-Jun 4; Xu, Lei-Luo 2
	2023-12-05
发表期刊	CHEMICAL GEOLOGY
ISSN	0009-2541
卷号	640 页码:12
通讯作者	Zhu, Wei-Guang(zhuweiguang@vip.gyig.ac.cn) ; Li, Chusi(cli@indiana.edu)
摘要	We use zircon trace elements and Hf-O isotopes, plus whole-rock chemical and Sr-Nd isotope compositions to investigate the controls on the chemistry of Neoproterozoic arc magmas. The samples are from the gabbrodiorite intrusion of the Gaojiacun mafic-ultramafic complex and from the Tongde diorite batholith of the Panxi Neoproterozoic magmatic belt in the western margin of the Yangtze craton, western China. Zircon U-Pb ages reveal that both intrusions are coeval, emplaced at similar to 820 Ma. Major element compositions of whole rocks and major silicate minerals indicate that the Tongde batholith formed from more evolved magma than the parental magma for the Gaojiacun intrusion. The mantle-normalized trace element patterns of whole rocks from both intrusions are similar, showing light REE enrichments and pronounced negative Nb-Ta anomalies. The Sr-Nd isotopic compositions of the whole rocks are also similar, plotting within or very close to the mantle array, indicating no to minor contamination with the upper crust. Zircon Hf-O isotopes indicate that the Gaojiacun magma has much higher epsilon(Hf) (6.26 +/- 0.52) and delta O-18 (7.0 +/- 0.3 parts per thousand) than the Tongde magma (epsilon(Hf) = 4.81 +/- 0.39; delta O-18 = 5.7 +/- 0.2 parts per thousand). The delta O-18 values of the Gaojiacun zircons are also higher than the normal mantle (delta O-18 = 5.3 +/- 0.6 parts per thousand). Zircon trace element compositions show that, despite their close spatial association (<10 km), the coeval intrusions have contrasting redox states, with the estimated fO(2) values of Delta FMQ+1.0 and Delta FMQ-0.7 for Tongde and Gaojiacun, respectively. The former is within the range of modern arc basalts, whereas the latter is lower than the average value of MORBs. The very low fO(2) of the Gaojiacun magma could be due to the presence of subducted oceanic sediments enriched in organic matter (OM) in the source or due to contamination with OM-rich sedimentary rocks in the upper crust. Since such crustal rocks have not been reported for the region, we prefer the former explanation. The preferred model is also supported by Sr-Nd-Hf-O isotopes. The results from this study reveal that both reduced and oxidized magma could be produced simultaneously in a subduction zone.
关键词	Zircon U-Pb ages Zircon Hf-O isotopes Magmatic fO(2) Sr-Nd isotopes Subduction magmatism Western China
DOI	10.1016/j.chemgeo.2023.121735
收录类别	SCI
语种	英语
资助项目	National Natural Science Foundation of China[42172092] ; National Natural Science Foundation of China[42121003] ; National Natural Science Foundation of China[42206051] ; Guizhou Provincial 2021 Science and Technology Subsidies[GZ2021SIG]
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:001092661200001
出版者	ELSEVIER
WOS关键词	SOUTH CHINA ; OXIDATION-STATE ; SW CHINA ; TECTONIC EVOLUTION ; ZIRCON MEGACRYSTS ; MAFIC INTRUSIONS ; SICHUAN PROVINCE ; YANBIAN TERRANE ; BLOCK EVIDENCE ; OCEANIC-CRUST
引用统计
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/183832
专题	深海极端环境与生命过程研究中心海洋地质与环境重点实验室
通讯作者	Zhu, Wei-Guang; Li, Chusi
作者单位	1.Chinese Acad Sci, Ctr Deep Sea Res, Inst Oceanol, Qingdao 266071, Peoples R China 2.Chinese Acad Sci, State Key Lab Ore Deposit Geochem, Inst Geochem, Guiyang 550081, Peoples R China 3.Indiana Univ, Dept Geol & Atmospher Sci, Bloomington, IN 47405 USA 4.East China Univ Technol, State Key Lab Nucl Resources & Environm, Nanchang 330013, Peoples R China 5.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao 266071, Peoples R China
第一作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	Yao, Junhua,Zhu, Wei-Guang,Li, Chusi,et al. Variations of Sr-Nd-Hf-O isotopes and redox conditions across a Neoproterozoic arc magmatic belt in the western margin of the Yangtze craton[J]. CHEMICAL GEOLOGY,2023,640:12.
APA	Yao, Junhua,Zhu, Wei-Guang,Li, Chusi,Bai, Zhong-Jie,Wang, Yan-Jun,&Xu, Lei-Luo.(2023).Variations of Sr-Nd-Hf-O isotopes and redox conditions across a Neoproterozoic arc magmatic belt in the western margin of the Yangtze craton.CHEMICAL GEOLOGY,640,12.
MLA	Yao, Junhua,et al."Variations of Sr-Nd-Hf-O isotopes and redox conditions across a Neoproterozoic arc magmatic belt in the western margin of the Yangtze craton".CHEMICAL GEOLOGY 640(2023):12.

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