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Serpentinization and the Formation of H2 and CH4 on Celestial Bodies (Planets, Moons, Comets).

Holm NG, Oze C, Mousis O, Waite JH, Guilbert-Lepoutre A - Astrobiology (2015)

Bottom Line: The continual and elevated production of H2 is capable of reducing carbon, thus initiating an inorganic pathway to produce organic compounds.The production of H2 and H2-dependent CH4 in serpentinization systems has received significant interdisciplinary interest, especially with regard to the abiotic synthesis of organic compounds and the origins and maintenance of life in Earth's lithosphere and elsewhere in the Universe.Whether deep in Earth's interior or in Kuiper Belt Objects in space, serpentinization is a feasible process to invoke as a means of producing astrobiologically indispensable H2 capable of reducing carbon to organic compounds.

View Article: PubMed Central - PubMed

Affiliation: 1 Department of Geological Sciences, Stockholm University , Stockholm, Sweden .

ABSTRACT
Serpentinization involves the hydrolysis and transformation of primary ferromagnesian minerals such as olivine ((Mg,Fe)2SiO4) and pyroxenes ((Mg,Fe)SiO3) to produce H2-rich fluids and a variety of secondary minerals over a wide range of environmental conditions. The continual and elevated production of H2 is capable of reducing carbon, thus initiating an inorganic pathway to produce organic compounds. The production of H2 and H2-dependent CH4 in serpentinization systems has received significant interdisciplinary interest, especially with regard to the abiotic synthesis of organic compounds and the origins and maintenance of life in Earth's lithosphere and elsewhere in the Universe. Here, serpentinization with an emphasis on the formation of H2 and CH4 are reviewed within the context of the mineralogy, temperature/pressure, and fluid/gas chemistry present in planetary environments. Whether deep in Earth's interior or in Kuiper Belt Objects in space, serpentinization is a feasible process to invoke as a means of producing astrobiologically indispensable H2 capable of reducing carbon to organic compounds.

No MeSH data available.


Related in: MedlinePlus

Central temperature of a 2 km radius comet nucleus, under the influence of heating by the radioactive decay of short-lived nuclides 26Al and 60Fe, as a function of time after formation (no accretional heating is accounted for here). The dashed line highlights the melting point of water. Each solid line represents the evolution of the central temperature after a specific formation time, from 0 (top curve) to 3 million years (bottom curve) since the formation time affects the effective amount of decaying nuclides contained in the body. Thermophysical parameters like thermal conductivity or composition used in the simulations (performed with the model described by Guilbert-Lepoutre et al., 2011) are standard for comets and within the range of realistic values described by other authors.
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f4: Central temperature of a 2 km radius comet nucleus, under the influence of heating by the radioactive decay of short-lived nuclides 26Al and 60Fe, as a function of time after formation (no accretional heating is accounted for here). The dashed line highlights the melting point of water. Each solid line represents the evolution of the central temperature after a specific formation time, from 0 (top curve) to 3 million years (bottom curve) since the formation time affects the effective amount of decaying nuclides contained in the body. Thermophysical parameters like thermal conductivity or composition used in the simulations (performed with the model described by Guilbert-Lepoutre et al., 2011) are standard for comets and within the range of realistic values described by other authors.

Mentions: The effect of radiogenic heating on comets is extremely uncertain, given the number of poorly constrained parameters involved, such as composition, initial internal structure, formation time, radioactive isotope content, porosity, or thermal conductivity. However, having a very short lifetime, the effectiveness of 26Al in heating comet interiors strongly depends on the nucleus formation time with respect to formation of calcium-aluminum-rich inclusions. Indeed, Irvine et al. (1980), Wallis (1980), and Prialnik et al. (1987) showed that, depending on the amount of 26Al related to the still poorly constrained comet formation time, the heat produced would be sufficient to melt water ice, in particular, in the case of objects with radii larger than 6 km. Thermal histories are also very sensitive to the material thermal conductivity (Haruyama et al., 1993). Prialnik and Podolak (1995) showed that, depending on the object's size, thermal conductivity, porosity, and initial composition (whether water ice is initially amorphous or crystalline), the early thermal evolution under the influence of 26Al decay could lead to various final configurations, ranging from pristine structures being thoroughly preserved to extensive melting of the ice contained in these objects. Here, we show similar results obtained with a model fully described by Guilbert-Lepoutre et al. (2011). In this model, the temperature distribution is computed inside an object and at its surface as a function of time and orbital position. For a set of initial thermophysical parameters typical for comets, we illustrate the same effect as Prialnik and Podolak (1995) that different formation times (or equivalent, different initial amounts of 26Al) might result in various final structures ranging from fully differentiated to completely pristine (Fig. 4). In summary, specific results on the early heating of comets by radioactive isotopes alone thus require detailed investigations on comet formation processes and timescales, which are not constrained yet, but so far all models are consistent with a potential occurrence of liquid water inside comets for a given set of realistic initial parameters.


Serpentinization and the Formation of H2 and CH4 on Celestial Bodies (Planets, Moons, Comets).

Holm NG, Oze C, Mousis O, Waite JH, Guilbert-Lepoutre A - Astrobiology (2015)

Central temperature of a 2 km radius comet nucleus, under the influence of heating by the radioactive decay of short-lived nuclides 26Al and 60Fe, as a function of time after formation (no accretional heating is accounted for here). The dashed line highlights the melting point of water. Each solid line represents the evolution of the central temperature after a specific formation time, from 0 (top curve) to 3 million years (bottom curve) since the formation time affects the effective amount of decaying nuclides contained in the body. Thermophysical parameters like thermal conductivity or composition used in the simulations (performed with the model described by Guilbert-Lepoutre et al., 2011) are standard for comets and within the range of realistic values described by other authors.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4523005&req=5

f4: Central temperature of a 2 km radius comet nucleus, under the influence of heating by the radioactive decay of short-lived nuclides 26Al and 60Fe, as a function of time after formation (no accretional heating is accounted for here). The dashed line highlights the melting point of water. Each solid line represents the evolution of the central temperature after a specific formation time, from 0 (top curve) to 3 million years (bottom curve) since the formation time affects the effective amount of decaying nuclides contained in the body. Thermophysical parameters like thermal conductivity or composition used in the simulations (performed with the model described by Guilbert-Lepoutre et al., 2011) are standard for comets and within the range of realistic values described by other authors.
Mentions: The effect of radiogenic heating on comets is extremely uncertain, given the number of poorly constrained parameters involved, such as composition, initial internal structure, formation time, radioactive isotope content, porosity, or thermal conductivity. However, having a very short lifetime, the effectiveness of 26Al in heating comet interiors strongly depends on the nucleus formation time with respect to formation of calcium-aluminum-rich inclusions. Indeed, Irvine et al. (1980), Wallis (1980), and Prialnik et al. (1987) showed that, depending on the amount of 26Al related to the still poorly constrained comet formation time, the heat produced would be sufficient to melt water ice, in particular, in the case of objects with radii larger than 6 km. Thermal histories are also very sensitive to the material thermal conductivity (Haruyama et al., 1993). Prialnik and Podolak (1995) showed that, depending on the object's size, thermal conductivity, porosity, and initial composition (whether water ice is initially amorphous or crystalline), the early thermal evolution under the influence of 26Al decay could lead to various final configurations, ranging from pristine structures being thoroughly preserved to extensive melting of the ice contained in these objects. Here, we show similar results obtained with a model fully described by Guilbert-Lepoutre et al. (2011). In this model, the temperature distribution is computed inside an object and at its surface as a function of time and orbital position. For a set of initial thermophysical parameters typical for comets, we illustrate the same effect as Prialnik and Podolak (1995) that different formation times (or equivalent, different initial amounts of 26Al) might result in various final structures ranging from fully differentiated to completely pristine (Fig. 4). In summary, specific results on the early heating of comets by radioactive isotopes alone thus require detailed investigations on comet formation processes and timescales, which are not constrained yet, but so far all models are consistent with a potential occurrence of liquid water inside comets for a given set of realistic initial parameters.

Bottom Line: The continual and elevated production of H2 is capable of reducing carbon, thus initiating an inorganic pathway to produce organic compounds.The production of H2 and H2-dependent CH4 in serpentinization systems has received significant interdisciplinary interest, especially with regard to the abiotic synthesis of organic compounds and the origins and maintenance of life in Earth's lithosphere and elsewhere in the Universe.Whether deep in Earth's interior or in Kuiper Belt Objects in space, serpentinization is a feasible process to invoke as a means of producing astrobiologically indispensable H2 capable of reducing carbon to organic compounds.

View Article: PubMed Central - PubMed

Affiliation: 1 Department of Geological Sciences, Stockholm University , Stockholm, Sweden .

ABSTRACT
Serpentinization involves the hydrolysis and transformation of primary ferromagnesian minerals such as olivine ((Mg,Fe)2SiO4) and pyroxenes ((Mg,Fe)SiO3) to produce H2-rich fluids and a variety of secondary minerals over a wide range of environmental conditions. The continual and elevated production of H2 is capable of reducing carbon, thus initiating an inorganic pathway to produce organic compounds. The production of H2 and H2-dependent CH4 in serpentinization systems has received significant interdisciplinary interest, especially with regard to the abiotic synthesis of organic compounds and the origins and maintenance of life in Earth's lithosphere and elsewhere in the Universe. Here, serpentinization with an emphasis on the formation of H2 and CH4 are reviewed within the context of the mineralogy, temperature/pressure, and fluid/gas chemistry present in planetary environments. Whether deep in Earth's interior or in Kuiper Belt Objects in space, serpentinization is a feasible process to invoke as a means of producing astrobiologically indispensable H2 capable of reducing carbon to organic compounds.

No MeSH data available.


Related in: MedlinePlus