Potassium isotopic composition of low-temperature altered oceanic crust and its impact on the global K cycle

doi:10.1016/j.gca.2021.08.001

	Potassium isotopic composition of low-temperature altered oceanic crust and its impact on the global K cycle
	Liu, Haiyang 1,2,3,4,5; Xue, Ying-Yu 1,2,3; Zhang, Guoliang 1,2,3; Sun, Wei-Dong1,2,3,6 ; Tian, Zhen 4,5; Tuller-Ross, Brenna 4,5; Wang, Kun4,5
	2021-10-15
发表期刊	GEOCHIMICA ET COSMOCHIMICA ACTA
ISSN	0016-7037
卷号	311 页码:59-73
通讯作者	Liu, Haiyang([email protected]) ; Wang, Kun([email protected])
摘要	To constrain the behavior of K isotopes during the low-temperature alteration of oceanic crust and reveal its impact on the global K cycle, we measured the K isotopic compositions of 49 fresh and altered basalts recovered from the Integrated Ocean Drilling Program (IODP) Sites U1365 (similar to 100 Ma) and U1368 (similar to 13.5 Ma) in the South Pacific Ocean. The measured basalts representing the uppermost oceanic crust have been subjected to low-temperature (<150 degrees C) alteration of different types and intensities as reflected by different secondary mineral modal abundances and element mobility. Both Sites have remarkably low sedimentation rates (0.71 and 1.1 m/Myr, respectively). The altered basalts from both Sites show higher K2O contents and K/Nb ratios than fresh basalts, suggesting the addition of K during low-temperature alteration. The measured delta K-41 values of the altered basalts vary over a large range (-0.76 parts per thousand to -0.17 parts per thousand) compared to unaltered basalts, indicating significant K isotopic fractionation during low-temperature alteration of the oceanic crust. We propose that the K isotopic characteristics of the altered basalts were caused by the combined effects of equilibrium and kinetic isotopic fractionations between seawater and alteration minerals during the incorporation and adsorption of K into alteration minerals. A weighted average delta K-41 value of -0.40 +/- 0.33 parts per thousand (2sd) is given for the low-temperature altered oceanic crust (AOC) at Sites U1365 and U1368, which is indistinguishable from the fresh N-MORB value (-0.44 +/- 0.17 parts per thousand), but significantly lower than its K source, i.e., seawater {delta K-41 = +0.12 +/- 0.07 parts per thousand, 2sd). Therefore, low-temperature AOC serves as an important sink for K and is a cause for the heavy K isotopic composition of seawater. In addition, the heterogeneous K isotopic compositions of the low-temperature AOC, together with large scale fractionation during various crustal processes, further highlights the utility of the K isotope system to trace subducted crustal materials. (C) 2021 Elsevier Ltd. All rights reserved.
关键词	K isotopes K oceanic budget Low temperature seafloor alteration IODP U1365 and U1368 Global K cycle Mantle heterogeneity
DOI	10.1016/j.gca.2021.08.001
收录类别	SCI
语种	英语
资助项目	Chinese Academy of Sciences[XDB42020303]; National Natural Science Foundation of China[91858206]; National Natural Science Foundation of China[41903006]; China Postdoctoral Science Foundation[Y9KY06110H]; China Postdoctoral Science Foundation[2020T130656]; AoShan Talents Cultivation Program - Qingdao National Laboratory for Marine Science and Technology[2017ASTCP-OS07]
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000693337600005
出版者	PERGAMON-ELSEVIER SCIENCE LTD
引用统计	被引频次：28[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/176383
专题	深海极端环境与生命过程研究中心
通讯作者	Liu, Haiyang; Wang, Kun
作者单位	1.Chinese Acad Sci, Ctr Deep Sea Res, Inst Oceanol, Qingdao 266071, Peoples R China 2.Pilot Natl Lab Marine Sci & Technol Qingdao, Lab Marine Mineral Resources, Qingdao 266237, Peoples R China 3.Chinese Acad Sci, Ctr Ocean Megasci, Qingdao 266071, Peoples R China 4.Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA 5.Washington Univ, McDonnell Ctr Space Sci, St Louis, MO 63130 USA 6.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
第一作者单位	中国科学院海洋研究所; 中国科学院海洋大科学研究中心
通讯作者单位	中国科学院海洋研究所; 中国科学院海洋大科学研究中心
推荐引用方式 GB/T 7714	Liu, Haiyang,Xue, Ying-Yu,Zhang, Guoliang,et al. Potassium isotopic composition of low-temperature altered oceanic crust and its impact on the global K cycle[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2021,311:59-73.
APA	Liu, Haiyang.,Xue, Ying-Yu.,Zhang, Guoliang.,Sun, Wei-Dong.,Tian, Zhen.,...&Wang, Kun.(2021).Potassium isotopic composition of low-temperature altered oceanic crust and its impact on the global K cycle.GEOCHIMICA ET COSMOCHIMICA ACTA,311,59-73.
MLA	Liu, Haiyang,et al."Potassium isotopic composition of low-temperature altered oceanic crust and its impact on the global K cycle".GEOCHIMICA ET COSMOCHIMICA ACTA 311(2021):59-73.

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