Methane, Hydrogen and Helium in Hydrothermal Fluids at 21°N on the East Pacific Rise

Welhan, J. A.; Craig, H.

doi:10.1007/978-1-4899-0402-7_17

Cited by 208 publications

(148 citation statements)

References 24 publications

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“…6. The estimated H 2 /CH 4 ratio of the HAKUREI fluid (0.022) is significantly lower than those of sediment-starved hydrothermal sites (>1, Welhan and Craig, 1983;Charlou et al, 2002;Kumagai et al, 2008;Proskurowski et al, 2008;Takai et al, 2008) that correspond to abiotic gas. Notably, the H 2 /CH 4 ratio of the HAKUREI fluid was comparable with those of thermogenic gases produced by hydrothermal experiment using the Guaymas Basin sediment (0.02~0.2: Seewald et al, 1994) as well as other sediment-related hydrothermal sites (Fig.…”

Section: H 2 /Ch 4 Ratiomentioning

confidence: 74%

Gas geochemical characteristics of hydrothermal plumes at the HAKUREI and JADE vent sites, the Izena Cauldron, Okinawa Trough

et al. 2010

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Section: H 2 /Ch 4 Ratiomentioning

confidence: 74%

Gas geochemical characteristics of hydrothermal plumes at the HAKUREI and JADE vent sites, the Izena Cauldron, Okinawa Trough

et al. 2010

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“…A starting point for these considerations is the abiogenic source on earth today, but estimates of this flux range over 2 orders of magnitude [Welhan and Craig, 1983;Kasting, 2005;Sorokhtin et al, 2001;Emmanuel and Ague, 2007;Cannat et al, 2010]. In this note, hydrothermal fluxes of abiogenic methane and hydrogen from mid-ocean ridges are estimated on the basis of gas concentrations that have been observed in vent fluids and the dependence of these concentrations on the type of host rock.…”

Section: Introductionmentioning

confidence: 98%

“…[5] Following the initial discovery of hydrothermal vents in the ocean, Welhan and Craig [1983] calculated an abiogenic methane flux of 4 × 10 9 mol yr −1 from mid-ocean ridges according to the degassing rate of 3 He from the mantle and the CH 4 / 3 He ratio observed at 21°N on the EPR. At that time, hydrothermal systems on slow-spreading ridges such as the Mid-Atlantic Ridge (MAR) had yet to be discovered.…”

Section: Introductionmentioning

confidence: 99%

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A note on the fluxes of abiogenic methane and hydrogen from mid‐ocean ridges

Keir¹

2010

Geophysical Research Letters

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[1] The concentrations of methane and hydrogen in hydrothermal vent fluids issuing from mid-ocean ridges tend to fall into two groups, one with high concentrations of these gases in ultramafic-hosted vent fields and a second group with relatively lower concentrations in basalt-hosted vent fluids. Ultramafic-hosted systems, however, appear to be restricted to slow-spreading ridges and constitute only a fraction of the hydrothermal systems found there. In this note, the hydrothermal fluxes of methane and hydrogen have been calculated by estimating the percentages of the total subsurface hydrothermal circulation that circulate through each type of host rock. Even though the percentage of the total subsurface flow that is affected by serpentinization appears to be rather small (8%), it still appears that this process produces about 70% of the total mid-ocean flux of these gases. The total production of methane and hydrogen is calculated to be about 20 × 10 9 mol yr −1 and 190 × 10 9 mol yr −1 , respectively. The hydrogen flux is comparable to that most recently calculated on the basis of the rate of hydration of mantle rock in newly formed crust and the stoichiometry of the serpentinization reaction. This suggests that, except for the production of methane, a major portion of the hydrogen produced in the subsurface is not consumed before venting. Citation: Keir, R. S.(2010), A note on the fluxes of abiogenic methane and hydrogen from mid-ocean ridges, Geophys.

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“…3). Production of hydrogen and methane upon interaction of seawater with hot olivine is ubiquitous in hydrothermal vents and in the water column along mid-ocean ridges (Welhan & Craig, 1983;Charlou et al 1998). The biogenic implications of the production of reduced gas has been discussed by Sleep et al (2004).…”

Section: The Origin Of Terrestrial Water and The Source Of Hydrogen Amentioning

confidence: 99%

The terrestrial craddle of life

Albarède

Blichert‐Toft

2009

Origins of Life: Self-Organization and/or Biological Evolution?

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Abstract. The Miller and Urey experiment in which amino acids were produced by electrical discharges in an atmosphere of water, methane, and ammonia was dismissed as being inconsistent with the secondary origin and the oxidizing character of the atmosphere. Since then, it has been found that simple geochemical arguments favor a dry accretion of the Earth and late delivery of water from the outer Solar System forming the primordial hydrosphere. This ocean of water must have interacted with the underlying terrestrial magma ocean, the existence of which is now well documented by evidence from the extinct radioactivity of 146 Sm (T 1/2 = 103 Ma) in Archean rocks. Water-hot rock interaction, with its hallmark reaction of serpentinization, produced enormous amounts of H 2 , which interacted with nitrogen and carbon dioxide to form CH 4 and NH 3 . From this follows that the Miller and Urey experiment should be reinstated as the main template of the origin of life.Sustainable life needs nutrients that can be steadily resupplied, most notably phosphate for which mid-ocean ridges act as a sink. In the modern world, phosphate is brought to the ocean by the erosion of continents, which are the hallmark of plate tectonics. On Earth, the elevation contrast between continents and abyssal plains is a result of plate tectonics: granitic rocks form by dehydration and melting of wet basaltic rocks at subduction zones. Life does not seem to be sustainable without plate tectonics, and plate tectonics in turn seems to result from the injection of water into the mantle by the subduction process, which "softens" mantle material and enhances convection. The earliest continental crust of modern affinity identified so far is attested to by Hadean detrital granitic zircons (ZrSiO 4 ) present in the Archean Jack Hills conglomerates (West Australia). This crust seems to have formed by remelting a primordial ∼4.35 Ga old crust extremely enriched in incompatible elements and which may have been derived from the early differentiation of the planet.The emergence of life therefore is conditioned by the interaction between magma and water, which excludes small planets such as the Moon, and possibly Mars, with a thick lithosphere of buoyant plagioclase. Life survival depends on a regime of plate tectonics, which again excludes Mars with its stagnant lithospheric lid, and Venus which probably lost its continents some 700 Ma ago after most of its surface water was engulfed into the mantle. It is also unlikely that a "water world" such as Europa may sustain Earth-like forms of life.

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Methane, Hydrogen and Helium in Hydrothermal Fluids at 21°N on the East Pacific Rise

Cited by 208 publications

References 24 publications

Gas geochemical characteristics of hydrothermal plumes at the HAKUREI and JADE vent sites, the Izena Cauldron, Okinawa Trough

Gas geochemical characteristics of hydrothermal plumes at the HAKUREI and JADE vent sites, the Izena Cauldron, Okinawa Trough

A note on the fluxes of abiogenic methane and hydrogen from mid‐ocean ridges

The terrestrial craddle of life

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