11:45 〜 12:00
[PCG20-11] Micrometer-scale distributions of small organic compounds in meteorites: implications to organic synthesis before asteroid accretion
★Invited Papers
キーワード：質量分析イメージング、隕石、有機物、原始太陽系円盤
Carbonaceous chondrites contain diverse small soluble organic compounds that formed and processed in the early solar system, including in the proto-solar nebula, proto-solar disk, and asteroids. These organic compounds may provide hints for understanding the early evolution of the solar system. In most cases, these organic compounds have been investigated in extracts of several hundred milligrams of meteorite powders due to the lack of suitable analytical methods in less than millimeter-scale resolution. Thus, their spatial distributions have been unclear. We investigated micrometer-scale distributions of small organic compounds in two carbonaceous chondrites (Murchison and NWA 801) using a surface-assisted laser desorption/ionization system connected to a high mass-resolution mass spectrometer. Distributions of diverse mass signals (i.e., more than 220,000 signals) with different elemental compositions of organic compounds were acquired from the meteorites. The distributions were categorized into 20 clusters by hierarchical cluster analysis. One cluster is occupied by the signals that have diverse CHN1-2 and CHN1-2O compounds in each meteorite. These compounds contained mutual relationships of ±H2, ±CH2, ±H2O, and ±CH2O and showed highly similar distributions, indicating that they are the products of series reactions. The spatial distributions were highly heterogeneous due to the micro-scale difference in the abundance of these compounds, indicating the formation of these compounds on individual dust particles before asteroid accretion. The compositions of diverse small organic compounds associated with individual dust particles in meteorites are useful for understanding different histories of volatile evolution in the early solar system.