2006 Fiscal Year Final Research Report Summary
Basic research of shock reaction on organic materials and its implication for cosmochemistry
| Project/Area Number |
16340172
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geochemistry/Astrochemistry
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| Research Institution | Nagoya University |
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Principal Investigator |
MIMURA Koichi Nagoya University, Graduate School of Environmental Studies, Associate Professor, 環境学研究科, 助教授 (80262848)
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| Project Period (FY) |
2004 – 2006
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| Keywords | IOM / D / ^<13>C / shock wave / devolatilization / organic materials / the Murchison meteorite |
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| Research Abstract |
Polycyclic aromatic hydrocarbons (PAHs) were impacted to study the behavior of PAHs against shock. We applied these results to estimate the survival degree of organic matter delivery by carbonaceous asteroids against their impacts pressures at the accretion stage of early Earth. The estimation suggests that a large quantity of prebiotic organic materials leading to life should have been delivered to the early Earth by the asteroids.
Shock recovery experiments on PAHs were carried out. In the experiments, we examined the shock-induced dehydrogenation of PAHs and δD vales and discussed the hydrogen amounts supplied to the Earth's atmosphere and interior during its formation. Then, we show that the cumulative amount of hydrogen in the Earth's interior at that point and its δD value were comparable to those already established for the Earth's interior.
Shock recovery experiments on Murchison meteorite samples were performed. δD values of the shocked Murchison showed an initial increase from +10.6%0 to +59.1%0 before declining to-87.6%0, as the dehydrogenation progressed. The behavior of δ^<13>C simply decreased from-15%0 to-7.65%0. The plot of those isotope data collected along devolatilization shows a variation curve that suggests the evolution of those isotopes in the meteorites. Shock is one of the processes effectively controlling the isotope features of the solar system.
We performed shock-recovery experiments on insoluble organic matter (IOM) purified from the Murchison meteorite. The shock selectively released D and ^<13>C from the IOM. The selective release of heavier isotopes from IOM would be due to its structure, in which D and ^<13>C-enriched parts are present as an inhomogeneity and are weakly attached to the main network. This effective release of D is probably an inherent result of shock. Thus, shock would effectively control the hydrogen isotope behavior of extraterrestrial organic matter during the evolution of the solar nebula.
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