(2020) I-Xe Dating of Solar Noble Gas-Rich Meteorites
Arai K, Takenouchi A, Sumino H & Tachibana S
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01g: Room 1, Tuesday 23rd June 08:06 - 08:09
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Hi Koharu. What fraction of 127I did you convert to 128Xe for your experiments? You say that you can increase this fraction by increaing the neutron flux. In practical terms how would you achive that? There appears to be a bit of scatter in your data for example Figure 11a. Do you know what could be causing this scatter?
Thank you for your question. The conversion rate was 2.1x10-5. In this study samples were irradiated in the reactor for 3 days. We are planning to expand the irradiation duration from three days to three weeks for out next experiments. This scatter may be due to the low production of 128Xe.
Hi, 10 million years after CAI is later than many other estimates for gas dissipation. What are the implications for giant planet growth and migration if the gas survives this long?
Thank you for your question. Ten million years seems longer than the observational estimate of lifetime of other disks. But ten million years here is the time for complete gas dissipation, which cannot be determined by the observation. So the timing determined in this study is likely to be longer than the observational estimate. Although we need to take more data, the lifetime of the solar system protoplanetary disk could still be within the variation of disk lifetime. As for the planet migration, the type I migration occurs within less than 1 million years. Thus this type of migration may not have worked efficiently in the Solar System. The type II migration may have occurred within the disk lifetime and the degree of migration should depend on when the gas giant formation occurred. We hope the disk lifetime estimated from meteorites can put a constraint on the timing of gas giant formation.
Zag is H3-6, so that hour I-Xe data would have mixed information? How different types distribute between light and dark clasts? Why graph(c) data show better linearity than other samples?
Thank you for your question. Both dark and light portions of Zag contain different petrologic types. The I-Xe data should contain those from different petrologic types. The data used to obtain the isochron was only from high temperature fractions, and the effect of different degrees of thermal metamorphism would be minimal. It is currently not clear why the isochron (c) has the better linearity than the others.
How sure are you that the relationship between I-Xe ages and SW is related to gas dissipation? Is it possible that the dark lithology is dark because it had a different history than the light one? This history could have involved spending more time in the superficial regolith were SW was acquired. This would also be in agreement with the dark lithology having lower I-Xe ages as these might have been partially reset by regolith processing. If I'm not mistaken Rubin et al. (MAPS, 2002) interpreted the dark lithology as a shocked version of the light lithology.
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