气候变化领域集成服务门户(CCPortal): A CO2 greenhouse efficiently warmed the early Earth and decreased seawater 18O/16O before the onset of plate tectonics

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DOI	10.1073/pnas.2023617118
	A CO2 greenhouse efficiently warmed the early Earth and decreased seawater 18O/16O before the onset of plate tectonics
	Herwartz D.; Pack A.; Nagel T.J.
发表日期	2021
ISSN	0027-8424
卷号	118 期号:23
英文摘要	The low 18O/16O stable isotope ratios (δ18O) of ancient chemical sediments imply ∼70 °C Archean oceans if the oxygen isotopic composition of seawater (sw) was similar to modern values. Models suggesting lower δ18Osw of Archean seawater due to intense continental weathering and/or low degrees of hydrothermal alteration are inconsistent with the triple oxygen isotope composition (Δ'17O) of Precambrian cherts. We show that high CO2 sequestration fluxes into the oceanic crust, associated with extensive silicification, lowered the δ18Osw of seawater on the early Earth without affecting the Δ'17O. Hence, the controversial long-term trend of increasing δ18O in chemical sediments over Earth's history partly reflects increasing δ18Osw due to decreasing atmospheric pCO2. We suggest that δ18Osw increased from about −5% at 3.2 Ga to a new steady-state value close to −2% at 2.6 Ga, coinciding with a profound drop in pCO2 that has been suggested for this time interval. Using the moderately low δ18Osw values, a warm but not hot climate can be inferred from the δ18O of the most pristine chemical sediments. Our results are most consistent with a model in which the “faint young Sun” was efficiently counterbalanced by a high-pCO2 greenhouse atmosphere before 3 Ga. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	Archean; Climate; Faint young Sun; Plate tectonics; Triple oxygen isotopes
语种	英语
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/238526
作者单位	Institut für Geologie und Mineralogie, Universität zu Köln, Köln, 50674, Germany; Geowissenschaftliches Zentrum, Georg-August-Universität Göttingen, Göttingen, 37073, Germany; Department of Geoscience, Aarhus University, Aarhus C, 8000, Denmark
推荐引用方式 GB/T 7714	Herwartz D.,Pack A.,Nagel T.J.. A CO2 greenhouse efficiently warmed the early Earth and decreased seawater 18O/16O before the onset of plate tectonics[J],2021,118(23).
APA	Herwartz D.,Pack A.,&Nagel T.J..(2021).A CO2 greenhouse efficiently warmed the early Earth and decreased seawater 18O/16O before the onset of plate tectonics.Proceedings of the National Academy of Sciences of the United States of America,118(23).
MLA	Herwartz D.,et al."A CO2 greenhouse efficiently warmed the early Earth and decreased seawater 18O/16O before the onset of plate tectonics".Proceedings of the National Academy of Sciences of the United States of America 118.23(2021).