Coordinated In Situ Analyses of Organic Nanoglobules in the Sutter's Mill Meteorite.

摘要

The Sutter s Mill meteorite is a newly fallen carbonaceous chondrite that was collected and curated quickly after its fall (1). Preliminary petrographic and isotopic investigations suggest affinities to the CM2 carbonaceous chondrites. The primitive nature of this meteorite and its rapid recovery provide an opportunity to investigate primordial solar system organic matter in a unique new sample. Organic matter in primitive meteorites and chondritic porous interplanetary dust particles (CP IDPs) is commonly enriched in D/H and N-15/N-14 relative to terrestrial values (2-4). These anomalies are ascribed to the partial preservation of presolar cold molecular cloud material (2). Some meteorites and IDPs contain gm-size inclusions with extreme H and N isotopic anomalies (3-5), possibly due to preserved primordial organic grains. The abundance and isotopic composition of C in Sutter's Mill were found to be similar to the Tagish Lake meteorite (6). In the Tagish Lake meteorite, the principle carriers of large H and N isotopic anomalies are sub-micron hollow organic spherules known as organic nanoglobules (7). Organic nanoglobules are commonly distributed among primitive meteorites (8, 9) and cometary samples (10). Here we report in-situ analyses of organic nano-globules in the Sutter's Mill meteorite using UV fluorescence imaging, Fourier-transform infrared spectroscopy (FTIR), scanning transmission electron microscopy (STEM), NanoSIMS, and ultrafast two-step laser mass spectrometry (ultra-L2MS).