气候变化领域集成服务门户(CCPortal): Hornblendites as a record of differentiation, metasomatism and magma fertility in arc crust

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DOI	10.1016/j.chemgeo.2024.121974
	Hornblendites as a record of differentiation, metasomatism and magma fertility in arc crust
	Zhu, Ren-Zhi; Smith, Daniel J.; Wang, Fangyue; Qin, Jiang-Feng; Zhang, Chao; Zhao, Shaowei; Liu, Min; Zhang, Fangyi; Zhu, Yu; Lai, Shao-Cong
发表日期	2024
ISSN	0009-2541
EISSN	1872-6836
起始页码	650
卷号	650
英文摘要	The fractionation of hornblende is a common phenomenon in arc magmas, and gives rise to a number of notable geochemical characteristics. However, it is often cryptic, with limited direct petrographic evidence for the fractionation, or even presence of amphibole in volcanic suites. Newly identified hornblendites in the SE Tibet represent direct evidence for hornblende fractionation in the Gangdese arc. The hornblendites have age ranges from 95.3 +/- 0.2 to 92.6 +/- 0.2 Ma, recording magmatic activities over a ca. 2 Myr interval. Textural relationships indicate that hornblendites form by peritectic reactions between an evolving melt and earlier-formed clinopyroxenites. Relict clinopyroxenes and primitive pargasite record melt evolution from high Sr/Y basaltic andesite to dacite, during cooling from similar to 1050 degrees C to similar to 850 degrees C in the mid to lower crust. The clinopyroxene precursors interacted with water-rich high SiO2 fluids/melts at ca. 800 degrees C. Zircons have high delta O-18 values (up to 7.62 parts per thousand) and positive epsilon Hf(t) values (up to +13.0), but bulk rock data show high Sr-87/Sr-86 ratios (up to 0.7093) and negative epsilon(Nd)(t) values (ca. -3.2). This decoupled signature implies the primary magmatic source was metasomatized by 5-10% recycled subducted sediments. Magmas have a high oxygen fugacity (Delta NNO can up to +2.40) through a combination of metasomatism during subduction, and subsequent melt-mush interaction that is recorded by zoned hornblendes. Metasomatism, widespread and long-term fractionation of amphibole +/- garnet +/- clinopyroxene, and high oxygen fugacity, are all positive indicators for the fertility of arc magmas with respect to porphyry copper formation. This study demonstrates that late-stage melt-mush interaction can contribute to peritectic hornblendite formation and facilitate magma fertility.
英文关键词	Fractionation of hornblende; Arc magmas; Metasomatism; Melt-mush interaction; Porphyry copper fertility
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:001200707100001
来源期刊	CHEMICAL GEOLOGY
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/290532
作者单位	Northwest University Xi'an; University of Leicester; Hefei University of Technology; Chang'an University; Chinese Academy of Sciences
推荐引用方式 GB/T 7714	Zhu, Ren-Zhi,Smith, Daniel J.,Wang, Fangyue,et al. Hornblendites as a record of differentiation, metasomatism and magma fertility in arc crust[J],2024,650.
APA	Zhu, Ren-Zhi.,Smith, Daniel J..,Wang, Fangyue.,Qin, Jiang-Feng.,Zhang, Chao.,...&Lai, Shao-Cong.(2024).Hornblendites as a record of differentiation, metasomatism and magma fertility in arc crust.CHEMICAL GEOLOGY,650.
MLA	Zhu, Ren-Zhi,et al."Hornblendites as a record of differentiation, metasomatism and magma fertility in arc crust".CHEMICAL GEOLOGY 650(2024).