气候变化领域集成服务门户(CCPortal): Geochemical evidence of Milankovitch cycles in Atlantic Ocean ferromanganese crusts

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DOI	10.1016/j.epsl.2020.116651
	Geochemical evidence of Milankovitch cycles in Atlantic Ocean ferromanganese crusts
	Josso P.; van Peer T.; Horstwood M.S.A.; Lusty P.; Murton B.
发表日期	2021
ISSN	0012821X
卷号	553
英文摘要	Hydrogenetic ferromanganese crusts are considered a faithful record of the isotopic composition of seawater influenced by weathering processes of continental masses. Given their ubiquitous presence in all oceans of the planet at depths of 400–7000 meters, they form one of the most well-distributed and accessible records of water-mass mixing and climate. However, their slow accumulation rate and poor age constraints have to date limited their use to explore 100 ka paleoclimatic phenomena. Here it is shown how the Pb isotope signature and major element content of a Fe-Mn crust from the north-east Atlantic responded to changes in the intensity and geographic extent of monsoonal rainfall over West Africa, as controlled by climatic precession during the Paleocene. The studied high-spatial resolution (4 μm) laser-ablation multi-collector inductively coupled plasma mass spectrometer (LA-MC-ICP-MS) Pb isotope data is a nearly 2 order of magnitude improvement in spatial and temporal resolution compared to micro-drill subsamples. The record demonstrates cyclicity of the 206Pb/204Pb and 208, 207Pb/206Pb ratios at the scale of single Fe-Mn oxide laminae, in conjunction with variations in the Fe/Mn ratio, Al, Si and Ti content. Time-frequency analysis and astronomical tuning of the Pb isotope data demonstrates the imprint of climatic precession (∼20 ka) modulated by eccentricity (∼100 and 405 ka), yielding growth rates of 1.5–3.5 mm/Ma consistent with previous chemostratigraphic age models. In this context, boreal summer at the perihelion causes stronger insolation over West Africa, resulting in more intense and geographically extended monsoonal rainfalls compared to aphelion boreal summer conditions. This, in turn, influences the balance between the weathering endmembers feeding the north-east Atlantic basin. These results provide a new approach for calibrating Fe-Mn crust records to astronomical solutions, and allow their isotopic and chemical archive to be exploited with an improved temporal resolution of 1000–5000 years. © 2020 Copyright British Geological Survey (c) UKRI 2020
关键词	astronomical parameters astronomical tuning Fe-Mn crust ITCZ Pb isotopes West African Craton
英文关键词	Binary alloys; Ferroalloys; Inductively coupled plasma; Iron alloys; Iron metallography; Iron ores; Iron oxides; Isotopes; Laser ablation; Lead; Manganese alloys; Manganese metallography; Manganese nodules; Mass spectrometers; Radioactive elements; Titanium oxides; Weathering; Ferromanganese crusts; Geochemical evidence; High spatial resolution; Inductively coupled plasma mass spectrometer; Isotopic composition; North East Atlantic; Spatial and temporal resolutions; Time frequency analysis; Lead metallography; chemostratigraphy; crustal structure; ferromanganese deposit; geochemistry; intertropical convergence zone; isotopic composition; lead isotope; Milankovitch cycle; mixing; paleoclimate; rainfall; seawater; water mass; Atlantic Ocean; West African Craton; Lamiinae
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203157
作者单位	British Geological Survey, Environmental Science Centre, Keyworth, Nottingham, NG12 5GG, United Kingdom; University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, United Kingdom; National Oceanography Centre, Waterfront Campus, European Way, Southampton, SO14 3ZH, United Kingdom
推荐引用方式 GB/T 7714	Josso P.,van Peer T.,Horstwood M.S.A.,et al. Geochemical evidence of Milankovitch cycles in Atlantic Ocean ferromanganese crusts[J],2021,553.
APA	Josso P.,van Peer T.,Horstwood M.S.A.,Lusty P.,&Murton B..(2021).Geochemical evidence of Milankovitch cycles in Atlantic Ocean ferromanganese crusts.Earth and Planetary Science Letters,553.
MLA	Josso P.,et al."Geochemical evidence of Milankovitch cycles in Atlantic Ocean ferromanganese crusts".Earth and Planetary Science Letters 553(2021).