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| Titel |
Abiogenic hydrocarbons produced under upper-mantle pressure-temperature conditions |
| VerfasserIn |
Alexander F. Goncharov, Raja S. Chellappa, Anton Kolesnikov, Maddury Somayazulu, Vladimir G. Kutcherov, Russell J. Hemley |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041250
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| Zusammenfassung |
| There are growing evidences for abiogenic pathways of the petroleum production in the
deep Earth. The laboratory experiments under extreme pressures and temperatures
provide direct information about the chemical reactivity and stability of the natural oil
components. Here we present new results on formation of hydrocarbons at high pressures
and temperatures generated in diamond anvil cells (DAC). We use in situ Raman
spectroscopy in laser heated diamond anvil cells to monitor the chemical reactivity; Raman
spectroscopy and synchrotron x-ray diffraction are used to determine the reaction
products quenched to ambient temperature. We have explored chemical reactions in the
system consisting of CaCO3-H2O with either of the following mantle minerals:
San Carlos olivine, peridodite, and Rockport fayalite. We also studied chemical
reactivity of methane and ethane to explore possible routes to generate heavier
hydrocarbons. The pressure range of the experiments (3-6 GPa) are similar to those
studied by Kenney et al. [1] and Scott et al. [2] but temperatures up to 2500 K were
generated. At pressures in the 5-6 GPa range, methanogenesis was observed in the
olivine-calcite-water, fayalite-calcite-water system at temperatures greater than
2300 K and less than 800 K, respectively. We find that methane at 2-5 GPa and
1000-1500 K partially reacts and forms saturated hydrocarbons (C2-C4alkanes),
molecular hydrogen and graphite. Formation of methane in similar experiments
on ethane suggests reversibility of hydrocarbon formation. These results support
proposals of abiogenic pathways for the formation of hydrocarbons in the Earth’s upper
mantle.
1 Kenney, J. F., Kutcherov, V. G., Bendeliani, N. A. & Alekseev, V. A. The Evolution of
Multicomponent Systems at High Pressures: VI. The Thermodynamic Stability of the
Hydrogen-Carbon System: The Genesis of Hydrocarbons and the Origin of Petroleum. Proc.
Natl. Acad. Sci. U.S.A. 99, 10976-10981 (2002).
2 Scott, H.P., Hemley, R.J., Mao, H-K., Herschbach, D.R., Fried, L.E., Howard, W.M.,
and Bastea, S. Generation of methane in the Earth’s mantle: In situ high pressure-temperature
measurements of carbonate reduction, Proc. Nat. Acad. Sci. 39, 14023-14026 (2004). |
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