Computer Science
Scientific paper
Jul 1992
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992metic..27q.265m&link_type=abstract
Meteoritics, vol. 27, no. 3, volume 27, page 265
Computer Science
1
Scientific paper
In studies of acid residues, nitrogen and noble gases have so far been analyzed separately, most often by different heating techniques, and the associations between nitrogen and noble gas components are sought, assuming similar release patterns in both experiments (Tang et al., 1988). Here we present results from simultaneous analysis of N and noble gases of a microdiamond separate from the Murchison meteorite. The separation was carried out on a ~6-g sample, following the procedure of Amari et al 1991. After three combustion steps at 400 degrees C, 600 degrees C, and 800 degrees C in 0.1 torr O2, the sample is pyrolysed at 1200 degrees C, 1500 degrees C, and 1700 degrees C. N and noble gases have been analyzed in all the temperature fractions by standard procedures (Murty and Goswami, 1991). The peak release for He, Ne, and N occurred at 1200 degrees C, while for Ar, Kr, and Xe, the release is bimodal with peaks at 600 degrees C and 1200 degrees C. Release of He continued up to 1500 degrees C and the 3/4 ratio remained nearly constant throughout at (0.9+-0.1) X 10^-4. The Ne composition in the 800 degrees C fraction matches that of Ne-A2, but in subsequent temperature fractions (>=1200 degrees C) both 20/22 and 21/22 decrease, reaching the lowest values of 3.16 and 0.016 respectively at 1700 degrees C, clearly showing some admixture of Ne-E(H). The 1200 degrees C fraction, where 90% N is released, has delta^15N = -310o/oo. At higher temperatures (>=1500 degrees C) the delta^15N falls to -595o/oo. Both Kr and Xe in the 600 degrees C fraction are similar to Kr-Q and Xe-Q (Wieler et al., 1991). Xe in the 1200 degrees C fraction and beyond has 136/134 > 1, typical of Xe-HL; while in the 800 degrees C fraction 136/134 ~ 0.92 indicating that it is a mixture of Xe-HL and Xe-Q (or Xe-P3). Normalized to 82, the Kr ratios show enrichment at heavy isotopes and depletions at lighter ones, as normally observed (Frick, 1977) except in the 800 degrees C fraction where a signature resembling the HL pattern was found. Further work will be needed to confirm this observation. The suggestion for a Ne-E (H) component at >= 1200 degrees C as well as the drop in delta^15N at the high temperature steps (>= 1500 degrees C) could be due to the presence of a small amount of SiC in our separate. However the major N-component (~90%) with delta^15N = -310o/oo, wherein Xe-HL is released and the presence of Ne-A2 are consistent with the characteristic properties of C delta microdiamonds. References: Amari, S., Lewis, R.S., and Anders, E. (1991) Geochim. Cosmochim. Acta (Submitted); Frick, U. (1977) Proc. Lunar Sci. Conf. 8, 273; Murty, S.V.S. and Goswami, J.N. (1991) (Abstract) Lunar Planet. Sci. Conf. 22, 947; Tang Ming, Lewis, R.S., Anders, E., Grady, M.M., Wright, I.P., and Pillinger, C.T. (1988) Geochim. Cosmochim. Acta 52, 1221; Wieler, R., Anders, E., Baur, H., Lewis, R.S., and Singer, P. (1991) Geochim. Cosmochim. Acta 55, 1709.
Goswami Jitendra N.
Murty Sripada V. S.
Srinivasan Ganesan
No associations
LandOfFree
Nitrogen and Noble Gases in Microdiamonds from Murchison does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Nitrogen and Noble Gases in Microdiamonds from Murchison, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nitrogen and Noble Gases in Microdiamonds from Murchison will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1209569