气候变化领域集成服务门户(CCPortal): Crustal Growth Identified by High-δ18O Zircon and Olivine: A Perspective from Ultramafic Arc Cumulates in Southern Tibet

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DOI	10.1093/petrology/egad052
	Crustal Growth Identified by High-δ18O Zircon and Olivine: A Perspective from Ultramafic Arc Cumulates in Southern Tibet
	Wang, Jun; Wang, Qiang; Sun, Peng; Dan, Wei; Kerr, Andrew C.; Zhang, Zhi-Ping; Zhang, Le; Wei, Gangjian; Dong, Han; Hu, Wan-Long; Yang, Zong-Yong; Zhang, Xiu-Zheng; Qi, Yue
发表日期	2023
ISSN	0022-3530
EISSN	1460-2415
卷号	64 期号:8
英文摘要	In recent studies of crustal growth using global zircon Hf-O isotopic datasets, high-& delta;O-18 zircons are typically attributed to intra-crustal reworking during which very little juvenile mantle-derived magmas were added to the crust. Although arc magmas may originate from a high-& delta;O-18 mantle wedge, it has been difficult to decipher the contribution of high-& delta;O-18 mantle to zircon-saturated felsic magma due to superimposed intra-crustal processes. We address this issue by combining the data from high-& delta;O-18 zircon-bearing ultramafic cumulates and coeval lavas from a Cretaceous magmatic arc in southern Tibet. The cumulates mainly consist of different proportions of cumulus olivine and intercumulus amphibole. Amphibole analyses show a transition from increasing to decreasing Zr with increasing SiO2 (50-74 wt.%) contents in the intercumulus melts, indicating zircon saturation in late-stage interstitial melts. The & epsilon;Nd(t) values (2.4 & PLUSMN; 1.4) of the apatite grains crystallized before and after zircon remain almost constant. Interstitial zircons have & delta;O-18 (6.1-7.2 & PTSTHOUSND;) values similar to the earliest crystallized olivine (& delta;O-18 = 6.3-7.1 & PTSTHOUSND;) in the cumulates. The coeval lavas may represent the intercumulus melts extracted from amphibole-rich cumulates at different depths. Both the lavas and cumulates were ultimately derived from high-& delta;O-18 arc mantle modified by small amounts (<12%) of subducted sediments, and crystallized zircon during intra-crustal magma evolution without involving crustal contamination or melting. These high-& delta;O-18 zircons therefore are not products of crustal reworking, but record crustal growth during their crystallization (110 & PLUSMN; 2 Ma). Our study shows that the combination of zircon and olivine oxygen isotopes for ultramafic to felsic rocks is more effective than zircon data alone in evaluating the role of crustal growth vs. reworking in an arc system. The implication is that global zircon-based crustal evolution models that attribute all high-& delta;O-18 zircons to crustal reworking may conceal recent crustal growth.
关键词	crustal growth zircon olivine oxygen isotope Tibet
英文关键词	CALC-ALKALINE DIFFERENTIATION; RARE-EARTH-ELEMENTS; HF-O ISOTOPES; U-PB; OXYGEN ISOTOPES; CONTINENTAL-CRUST; INTRUSIVE ROCKS; LHASA TERRANE; RADIOGENIC ISOTOPES; WORKING REFERENCE
WOS研究方向	Geochemistry & Geophysics
WOS记录号	WOS:001038404700001
来源期刊	JOURNAL OF PETROLOGY
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/282793
作者单位	Chinese Academy of Sciences; Guangzhou Institute of Geochemistry, CAS; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; Cardiff University; Chinese Academy of Sciences; Guiyang Institute of Geochemistry, CAS; Chinese Academy of Sciences; Guangzhou Institute of Geochemistry, CAS
推荐引用方式 GB/T 7714	Wang, Jun,Wang, Qiang,Sun, Peng,et al. Crustal Growth Identified by High-δ18O Zircon and Olivine: A Perspective from Ultramafic Arc Cumulates in Southern Tibet[J],2023,64(8).
APA	Wang, Jun.,Wang, Qiang.,Sun, Peng.,Dan, Wei.,Kerr, Andrew C..,...&Qi, Yue.(2023).Crustal Growth Identified by High-δ18O Zircon and Olivine: A Perspective from Ultramafic Arc Cumulates in Southern Tibet.JOURNAL OF PETROLOGY,64(8).
MLA	Wang, Jun,et al."Crustal Growth Identified by High-δ18O Zircon and Olivine: A Perspective from Ultramafic Arc Cumulates in Southern Tibet".JOURNAL OF PETROLOGY 64.8(2023).