Mathematics – Logic
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufm.p11a1195w&link_type=abstract
American Geophysical Union, Fall Meeting 2009, abstract #P11A-1195
Mathematics
Logic
[6240] Planetary Sciences: Solar System Objects / Meteorites And Tektites
Scientific paper
Primitive meteorites contain up to 2 wt % C, much of it in the form of insoluble organic matter (IOM). Bulk analyses have revealed the IOM to be marked by large D and 15N enrichments relative to terrestrial values. Isotopic imaging studies have revealed the presence of `hotspots’, sub-μm to μm-sized regions of IOM exhibiting extreme isotope enrichments. An interesting subpopulation of organic grains, ’nanoglobules’, which have hollow, spherical morphologies, is known to account for a portion of these hot spots. Previous work has suggested that nanoglobules can be identified in situ by native UV fluorescence. The isotopic enrichments are believed to point to low-T chemical fractionations either in the interstellar medium (ISM) or the outer regions of the early Solar System. As part of a larger study investigating the origin and evolution of IOM in the Solar System, a correlated, in situ, microanalytical approach was employed to characterize local isotopic and morphological heterogeneities in IOM in the highly primitive chondrites QUE 99177 (CR3) and Tagish Lake (C-ung). Previous NanoSIMS ion imaging of a QUE 99177 section revealed the spatial and isotopic distribution of C in the matrix with a spatial resolution of 200 nm. Manual definition of >3300 C-rich regions in the NanoSIMS images indicates that grains smaller than 1 μm across, which account for 80% of the IOM area, have a size distribution that is similar to estimates of the size distribution of carbonaceous dust in the diffuse ISM, supporting an interstellar origin for the IOM. Micro-Raman spectroscopy, which is highly sensitive to the degree of disorder in carbonaceous materials, was attempted on the same regions analyzed by NanoSIMS in QUE 99177. Unfortunately, surface damage due to both the prior SIMS analyses and removal of a prior C coat precluded acquisition of useful Raman spectra. Consequently, future correlated work will entail performing Raman analyses on uncoated samples prior to SIMS analysis. Previous NanoSIMS and SEM investigations of a new sample of Tagish Lake revealed the presence of isotopically anomalous nanoglobules, so several pristine fragments from it were targeted for a UV fluorescence study. Only one of five fragments analyzed so far showed fluorescence, suggesting either that nanoglobules are not present in the specific fragments or that not all nanoglobules readily fluoresce. UV measurements of additional fragments as well as correlated Raman, SEM and NanoSIMS analyses of the same samples will help resolve the question.
Herd C. D.
Nittler Larry
Steele Andrew
Wende A. M.
No associations
LandOfFree
In situ characterization of organic matter in two primitive chondrites through correlated microanalytical techniques 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 In situ characterization of organic matter in two primitive chondrites through correlated microanalytical techniques, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and In situ characterization of organic matter in two primitive chondrites through correlated microanalytical techniques will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1766804