Abstract
Carbonaceous chondrites are known to contain a few wt. % organic matter whose majority consists of macromolecular organic compounds (e.g. Botta and Bada, 2002; Sephton, 2002). Minerals are suggested to have catalytic effects for the production and alteration processes of these organic materials (e.g. Wing and Bada, 1992; Kerridge, 1999). We conducted mapping measurements of Tagish Lake meteorite grains by Fourier Transform Infrared Micro-Spectroscopy (micro-FTIR) and Scanning Electron Microscopy and Energy Dispersion X-ray Spectrometry (SEM-EDS) for studying the distribution of minerals and organic matter. Tagish Lake was powdered and pressed between two pieces of Al discs to make the sample flat. The mapping area is 590 x 950 microns for micro-FTIR (Jasco IMV-4000 + FTIR-6200; resolution 12.5 microns) and SEM-EDS (JEOL JSM-5510LV + JED-2300). By the micro-FTIR mapping, heterogeneous distribution of aliphatic C-H and organic C-O was observed, and aliphatic C-H was distributed with phyllosilicate O-H. SEM-EDS elemental analysis revealed that aliphatic C-H rich portions were Mg rich and Fe, S poor. These results indicate that aliphatic C-H is coexisting with Mg-rich phyllosilicates.
