On the possible influence of extraterrestrial volatiles on Earth's climate and the origin of the oceans

Deming, David

doi:10.1016/s0031-0182(98)00144-8

Cited by 26 publications

(6 citation statements)

References 88 publications

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“…The resulting contribution to the total water reservoir in the Earth system would be of minor importance. In contradiction there is also a so-called extraterrestrial volatile-accretion hypothesis (ETV) postulating four to five orders of magnitude higher volatile accretion rates (Deming, 1999). If so, this effect would have to be taken into account as a water flux into the Earth system.…”

Section: Methodsmentioning

confidence: 99%

The fate of Earth’s ocean

Bounama

Franck

Bloh

2001

Hydrol. Earth Syst. Sci.

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Questions of how water arrived on the Earth's surface, how much water is contained in the Earth system as a whole, and how much water will be available in the future in the surface reservoirs are of central importance to our understanding of the Earth. To answer the question about the fate of the Earth's ocean, one has to study the global water cycle under conditions of internal and external forcing processes. Modern estimates suggest that the transport of water to the surface is five times smaller than water movement to the mantle, so that the Earth will lose all its sea-water in one billion years from now. This straightforward extrapolation of subduction-zone fluxes into the future seems doubtful. Using a geophysical modelling approach it was found that only 27% of the modern ocean will be subducted in one billion years. Internal feedbacks will not be the cause of the ocean drying out. Instead, the drying up of surface reservoirs in the future will be due to the increase in temperature caused by a maturing Sun connected to hydrogen escape to outer space.

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Section: Methodsmentioning

confidence: 99%

The fate of Earth’s ocean

Bounama

Franck

Bloh

2001

Hydrol. Earth Syst. Sci.

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“…A final source of 12 C-enriched carbon is extraterrestrial: as comets are 20-25% carbon by weight and have a δ 13 C value of −45 or lower (Arpigny et al, 2003;Delsemme, 1988;Jessberger et al, 1991;Jewitt et al, 1997;Messenger, 2000;Wyckoff et al, 2000), the impact of a reasonably large size comet should result in a decrease in the δ 13 C value of the rapidly exchangeable carbon cycle (Bowring et al, 1998;Deming, 1999;Kent et al, 2003a;Wilde and Quinby-Hunt, 1997). Accounting for a 2.5 decrease in deep water δ 13 C values in this way would require an extremely, but not impossibly, large comet: assuming cometary density of 1500 kg/m 3 , a 20-22 km-diameter comet would deliver the requisite ∼2200 Gt of carbon.…”

Section: Deep Ocean Shiftmentioning

confidence: 99%

Bolide summer: The Paleocene/Eocene thermal maximum as a response to an extraterrestrial trigger

Cramer

Kent

2005

Palaeogeography, Palaeoclimatology, Palaeoecology

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The standard paradigm that the Paleocene/Eocene thermal maximum (PETM) represents a threshold event intrinsic to Earth's climate and connected in some way with long-term warming has influenced interpretations of the geochemical, climate, and biological perturbations that occurred at this event. As recent high-resolution data have demonstrated that the onset of the event was geologically instantaneous, attempts to account for the event solely through endogenous mechanisms have become increasingly strained. The rapid onset of the event indicates that it was triggered by a catastrophic event which we suggest was most likely a bolide impact. We discuss features of the PETM that require explanation and argue that mechanisms that have previously been proposed either cannot explain all of these features or would require some sort of high-energy trigger. A bolide impact could provide such a trigger and, in the event of a comet impact, could contribute directly to the shape of the carbon isotope curve. We introduce a carbon cyle model that would explain the PETM by global warming following a bolide impact, leading to oxidation of terrestrial organic carbon stores built up during the late Paleocene. Our intention is to encourage other researchers to seriously consider an impact trigger for the PETM, especially in the absence of plausible alternative mechanisms.

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“…Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions Introduction CYCLING THROUGH subduction zones represents a major variable in the global mantle-ocean-atmosphere mass balance for some volatile components (Berner and Lasaga;Zhang and Zindler, 1993;Bebout, 1995Bebout, , 1996Javoy, 1997Javoy, , 1998Deming, 1999;Franck et al, 1999;Jarrard, 2003). Much effort has recently been aimed at constraining the quantities and geochemistry of subducting sediment (von Huene and Scholl, 1991;Rea and Ruff, 1996;Plank and Langmuir, 1998;Jarrard, 2003), and evaluating the magnitude and mechanisms of the movement of volatiles (emphasizing H 2 O and C) being subducted in sediments in active convergent margins.…”

Section: Please Scroll Down For Articlementioning

confidence: 99%

Field and Isotopic Evidence for Fluid Mobility in the Franciscan Complex: Forearc Paleohydrogeology to Depths of 30 Kilometers

Sadofsky

Bebout

2004

International Geology Review

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In the Franciscan Complex exposed in the California Coast and Diablo ranges (representing depths of up to 30 km in a Mesozoic to Early Tertiary accretionary prism), differences in porosity, permeability, and rheology impacted geometries and scales of fluid mobility and the deep entrainment of pore water (chemically evolved seawater). Carbon and O isotope compositions of abundant, texturally diverse CaCO 3 veins (most veins with δ 13 C VPDB = -11.0 to -3.0‰, δ 18 O VSMOW = +12.0 to +18.5‰) are in part consistent with control of fluid isotopic compositions by relatively local-scale exchange with large volumes of metaclastic host-rocks. Although this apparent local-scale equilibration, observed for some veins, complicates assessment of external sources for the fluids that produced these veins, many veins with elevated δ 18 O (relative to calculated rock-buffered values) could reflect up-dip flow of H 2 O released at greater depths and previously equilibrated with similar lithologies at higher temperatures (and sluggish reequilibration of the rocks with these externally derived fluids). In the Coastal Belt, differences in vein δ 13 C in adjacent coherent graywacke and shaley mélange zones may be due to preferential infiltration of the more permeable mélange zones by deeply derived CH 4 -bearing fluids, perhaps in part during exhumation and cooling. A number of variations in vein isotopic composition in individual exposures can be attributed to vein formation over a range of increasing T during underthrusting, then decreasing T during exhumation, and related to varying rheology (affecting permeability) within intercalated highly disrupted shales, sandstone-shale sequences (with interbedding at mm to cm scales), and more massive metagraywacke.Calculated fluid δ 18 O for veins in the Franciscan units peak metamorphosed at lower temperatures (Coastal Belt) spans the range of fluids venting in active accretionary prisms and producing forearc serpentinite seamounts (mostly 0 ± 3‰). In general, higher flux of aqueous fluid from depth in accretionary prisms, preventing reequilibration with rocks along its path, should favor expulsion of fluid with δ 18 O higher than that of seawater that could be traced in fluids along fault structures at shallower levels. Salinities of fluid inclusions in vein quartz are mostly lower than that of seawater, consistent with delivery of "fresher" aqueous fluids toward the surface along structural heterogeneities. Recent work on volatile and trace element contents of the Coast and Diablo ranges exposures of the Franciscan Complex indicates significant loss of structurally bound H 2 O (i.e., not pore water) due to clay-to-mica transitions, but at shallower levels than those for peak metamorphism of all units studied here (i.e., at <5 km). Much of the fluid flux through these rocks involved fluids liberated at greater depths, precipitating calcite and quartz along down-T, down-P paths, and mobilizing trace elements (e.g., B, Cs, perhaps also K, Rb, As, and Sb) liberated at higher temperatures. Ca...

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On the possible influence of extraterrestrial volatiles on Earth's climate and the origin of the oceans

Cited by 26 publications

References 88 publications

The fate of Earth’s ocean

The fate of Earth’s ocean

Bolide summer: The Paleocene/Eocene thermal maximum as a response to an extraterrestrial trigger

Field and Isotopic Evidence for Fluid Mobility in the Franciscan Complex: Forearc Paleohydrogeology to Depths of 30 Kilometers

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