Mineralogy and IR spectroscopy of the Tagish Lake C2 chondrite and enstatite chondrites

• Main Author: Izawa, Matthew Richard Mitsuomi
• Format: Text
• Language: unknown
• Published: Scholarship@Western 2008
• Subjects: X-ray diffraction; Reflectance infrared spectroscopy; Rietveld refinement; chondrules; CAI; parent body alteration; terrestrial alteration; meteorite grain density; Tagish; Tagish Lake
• Online Access: https://ir.lib.uwo.ca/digitizedtheses/4320; https://ir.lib.uwo.ca/context/digitizedtheses/article/8139/viewcontent/2023_10_26_Tagish_lake_and_E_chondrites_mineralogy_and_IR_spectroscopy_OCR.pdf

Sample-correlated X-ray diffraction (XRD) and diffuse-reflectance Fourier- transform infrared (DRIFTS) spectra were collected for seven samples of the Tagish Lake C2 chondrite and thirteen enstatite chondrites. A reconnaissance of the Tagish Lake chondrite was carried out using micro-XRD, SEM-EDX and EPMA. Modal mineral abundances were obtained from XRD data via Rietveld refinement. Grain densities were calculated for each sample based on the modal abundances. DRIFTS spectra are analogous to remote-sensing emission IR spectra, facilitating comparison with astronomical observations. Tagish Lake was found to be more varied in major mineralogy than has previously been reported. In addition to the documented carbonate-rich and carbonate-poor lithologies, a magnetite- and- sulphide-rich lithology, and a carbonaterich, siderite-dominated lithology have been observed. Several Tagish Lake samples may contain extraterrestrial sulphates. Terrestrially altered enstatite chondrites may be analogous to the regolith of certain rare M- and E-type asteroids (“W-class”) which possess a spectral feature consistent with hydrated minerals.