DOI: 10.1016/j.epsl.2020.116546
论文题名: Can volcanism build hydrogen-rich early atmospheres?
作者: Liggins P. ; Shorttle O. ; Rimmer P.B.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 550 语种: 英语
中文关键词: atmosphere
; early Earth
; hydrogen
; redox
; volcanic degassing
英文关键词: Earth atmosphere
; Efficiency
; Mixing
; Volcanoes
; Water recycling
; Atmospheric conditions
; Crustal recycling
; Greenhouse warming
; Prebiotic molecules
; Surface pressures
; Thermodynamical model
; Top of the atmospheres
; Volcanic outgassing
; Planets
; atmosphere
; crustal recycling
; degassing
; early Earth
; hydrogen
; Mars
; redox conditions
; volcanism
; water content
英文摘要: Hydrogen in rocky planet atmospheres has been invoked in arguments for extending the habitable zone via N2-H2 and CO2-H2 greenhouse warming, and providing atmospheric conditions suitable for efficient production of prebiotic molecules. On Earth and Super-Earth-sized bodies, where hydrogen-rich primordial envelopes are quickly lost to space, volcanic outgassing can act as a hydrogen source, provided it balances the hydrogen loss rate from the top of the atmosphere. Here, we show that both Earth-like and Mars-like planets can sustain atmospheric H2 fractions of several percent across relevant magmatic fO2 ranges. In general this requires hydrogen escape to operate somewhat less efficiently than the diffusion limit. We use a thermodynamical model of magma degassing to determine which combinations of magma oxidation, volcanic flux and hydrogen escape efficiency can build up appreciable levels of hydrogen in a planet's secondary atmosphere. On a planet similar to the Archean Earth and with a similar magmatic fO2, we suggest that the mixing ratio of atmospheric H2 could have been in the range 0.2-3%, from a parameter sweep over a variety of plausible surface pressures, volcanic fluxes, and H2 escape rates. A planet erupting magmas around the Iron-Wüstite (IW) buffer (i.e., ∼3 log fO2 units lower than the inferred Archean mantle fO2), but with otherwise similar volcanic fluxes and H2 loss rates to early Earth, could sustain an atmosphere with approximately 10-20% H2. For an early Mars-like planet with magmas around IW, but a lower range of surface pressures and volcanic fluxes compared to Earth, an atmospheric H2 mixing ratio of ∼2-8% is possible. On early Mars, this H2 mixing ratio could be sufficient to deglaciate the planet. However, the sensitivity of these results to primary magmatic water contents and volcanic fluxes show the need for improved constraints on the crustal recycling efficiency and mantle water contents of early Mars. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165116
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, United Kingdom; Institute of Astronomy, University of Cambridge, Cambridge, CB3 0HA, United Kingdom; Cavendish Astrophysics, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom; MRC Laboratory of Molecular Biology, Francis Crick Ave, Cambridge, CB2 0QH, United Kingdom
Recommended Citation:
Liggins P.,Shorttle O.,Rimmer P.B.. Can volcanism build hydrogen-rich early atmospheres?[J]. Earth and Planetary Science Letters,2020-01-01,550