气候变化领域集成服务门户(CCPortal): Potassium Isotope Fractionation During Magmatic Differentiation and the Composition of the Mantle

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DOI	10.1029/2020JB021543
	Potassium Isotope Fractionation During Magmatic Differentiation and the Composition of the Mantle
	Hu Y.; Teng F.-Z.; Helz R.T.; Chauvel C.
发表日期	2021
ISSN	21699313
卷号	126 期号:3
英文摘要	Stable potassium (K) isotopes are emerging as tracers of terrestrial recycling and planetary processes. These applications require well-defined K isotopic compositions for the mantle and the bulk silicate Earth (BSE). Both values are determined primarily by basalts formed via partial melting of the mantle. Basaltic melts experience igneous differentiation before reaching the surface, which may alter their isotopic compositions compared to their mantle sources. This study investigates K isotope fractionation during the differentiation and solidification of the Kilauea Iki lava lake, Hawaii, for which crystallization and thermal histories are well documented. High-precision K isotopic ratios (δ41K) are measured in 13 Kilauea Iki samples that cover its complete differentiation history, ranging from olivine-rich, high-MgO cumulates to increasingly differentiated, MgO-depleted samples. The limited δ41K range of −0.42 to −0.37‰ in all but one sample reveals no analytically resolvable fractionation across diverse bulk compositions, even though their bulk MgO contents varied from 26.9 to 2.37 wt.%. The lack of K isotopic fractionation is consistent with an absence of K-rich minerals in the crystallizing assemblage, where only plagioclase can accommodate a small amount of K. A highly differentiated vein displays the lowest δ41K of −0.47‰ among the Kilauea Iki suite, which is consistent with our modeling calculations that suggest measurable K isotope fractionation at more advanced magmatic differentiation stages. Combining our new results with literature data, we propose an average δ41K of −0.42 ± 0.08‰ (2SD) for the pristine mantle and of −0.42 ± 0.07‰ (2SD) for the BSE. © 2021. American Geophysical Union. All Rights Reserved.
英文关键词	high-precision; isotope fractionation; Kilauea Iki lava lake; magmatic differentiation; potassium isotopes
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187268
作者单位	Isotope Laboratory, Department of Earth and Space Sciences, University of Washington, Seattle, WA, United States; United States Geological Survey, Reston, VA, United States; Institut de Physique du Globe de Paris, CNRS, Université de Paris, Paris, France; ISTerre, CNRS, Université Grenoble Alpes, Grenoble, France
推荐引用方式 GB/T 7714	Hu Y.,Teng F.-Z.,Helz R.T.,et al. Potassium Isotope Fractionation During Magmatic Differentiation and the Composition of the Mantle[J],2021,126(3).
APA	Hu Y.,Teng F.-Z.,Helz R.T.,&Chauvel C..(2021).Potassium Isotope Fractionation During Magmatic Differentiation and the Composition of the Mantle.Journal of Geophysical Research: Solid Earth,126(3).
MLA	Hu Y.,et al."Potassium Isotope Fractionation During Magmatic Differentiation and the Composition of the Mantle".Journal of Geophysical Research: Solid Earth 126.3(2021).