Living reference work entry
In meteoritic chemistry, globules or nanoglobules are microscopic, hollow (but sometimes solid), spherical to irregular organic grains present in the fine-grained matrix of carbonaceous chondrites (Fig. 1). Organic globules have also been reported in ordinary chondrites, Antarctic micrometeorites, interplanetary dust particles, and comets. Globule diameters range from less than 100 up to 2 μm. Many are enriched in deuterium and/or nitrogen-15 relative to the surrounding bulk insoluble organic matter, suggesting formation in extremely cold (less than 20 K) molecular cloud or solar nebula environments where such isotopic enrichments of organic matter are theorized to occur (Nakamura-Messenger et al. 2006). Some organic globules may also have formed on asteroid and/or planetesimal parent bodies through organic polymerization, such as the formose reaction, during aqueous processing (Cody et al. 2011).
KeywordsNitrogen Isotope Molecular Cloud Isotopic Enrichment Parent Body Solar Nebula
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