Thermal release of noble gases from meteoritic nanodiamonds: are P3 noble gases likely evolved at higher temperatures?

Fisenko, A. V.; Verchovsky, A. B.; Semjonova, L .F. and Wright, I. P. (2010). Thermal release of noble gases from meteoritic nanodiamonds: are P3 noble gases likely evolved at higher temperatures? In: 41st Lunar and Planetary Science Conference, 1-5 Mar 2010, Houston, TX, US.

URL: http://www.lpi.usra.edu/meetings/lpsc2010/pdf/2008...

Abstract

Introduction. It is generally accepted that the enrichment of heavy and light Xe isotopes in Xe-HL is associated with p- and r-process nucleosynthesis in type II supernovae. However these excess represent only a small fraction of Xe-HL in which an isotopically normal component dominates. The origin of the isotopically normal component remains unknown as does when and how the mixing with the anomalous nucleosynthetic components took place. Unsuccessful attempts to separate Xe-HL into individual components by a number of different methods have resulted in the conclusion that Xe-HL represents a single component formed before implantation into nanodiamonds. This component is released from nanodiamonds at relatively high temperatures during stepped pyrolysis. The other, isotopically normal nanodiamond component, P3, is liberated at significantly lower temperature. Recently, on the basis of experimental simulation of ion implantation into synthetic nanodiamonds, it was suggested that the high temperature release is also dominated by P3 noble gases i. e. HL is effectively the result of the release of a small amount of the highly anomalous supernova components along with P3 gases at the high temperature. According to this suggestion the isotopically anomalous and normal (P3) components have been trapped in the same energetic sites so that during release by pyrolysis they cannot be separated from each other (and therefore appear as a single component). The suggestion is based on the similarity in the release pattern of artificially implanted noble gases into synthetic ultradispersed nanodiamonds (UDD) and P3 and HL noble gases from meteoritic nanodiamonds. Here we examine this suggestion using arguments which have not been considered by the authors of the original concept.

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