The effect of pyridine treatment on phase Q: Orgueil and Allende

Abstract

Abstract-Marrocchi et al. (2005) reported that low-temperature fractions of heavy noble gases were largely removed upon pyridine treatment of the Orgueil CI meteorite. As pyridine is known to induce the swelling of the macromolecular network of organic matter, they concluded that the low-temperature phase Q is macromolecular organic carbon. However, Busemann et al. (2008) showed that pyridine had no significant effect on the noble gas contents for other very primitive meteorites, such as CM and CR. Therefore, we prepared an HF-HCl residue and the pyridine-treated residue of Orgueil, and re-examined the results of Marrocchi et al. (2005) by analyzing all noble gases. We confirmed that heavy noble gases are surely removed by the pyridine treatment, but the degree of the loss of heavy noble gases is generally small, and is even smaller for the lighter noble gases. Furthermore, we could not observe the evidence of Xe isotopic ratios by removing only phase Q after the pyridine treatment. We further prepared the HF-HCl residue and the pyridine-treated residue of the Allende CV3 meteorite and performed noble gas analyses. For Allende, there is no significant change in the elemental abundances after the pyridine treatment. These results suggest that only Orgueil is special, and it is likely that the gas loss of the Orgueil residue is due to the loss of some kind of organic matter that was formed and that adsorbed the fractionated Q and HL gases during the aqueous alteration within the parent body of Orgueil.

Noble gases in oxidized residue prepared from the Saratov L4 chondrite and Raman spectroscopic study of residues to characterize phase Q

“…Matsuda et al. () indicated that loss of Q‐gases was only the case for Orgueil and that it was due to the loss of some kind of organic matter that formed and adsorbed the fractionated Q‐ and HL gases during aqueous alteration of Orgueil's parent body. However, Spring et al.…”

On the Effect of Laser-Induced Heating in a Raman Spectroscopic Study of Carbonaceous Material in Meteorite

“…We also used CS 2 to remove elemental sulfur during the chemical treatment. [8,9] We investigated the effect of laser-induced heating on Raman peak positions, FWHMs, and intensity ratios of G and D bands for this sample.…”

“…[5] G-peak positions also increase with increasing degree of crystallinity. [6,10] The pyridine treatment did not affect the carbon structure [8] , but the acid leaching likely affected it. [9] Thus Raman spectroscopic parameters are good indicators for the metamorphism of meteorites, and their precise measurements are very important.…”

“…[1][2][3] Typical Raman spectra of carbonaceous matter in meteorites show strong lines of the G band (1580 cm À1 ) and the D band (1350 cm À1 ). [4][5][6][7][8][9] The G band is observed in all disordered graphitic carbon and is assigned to the E 2 g vibration mode. D band is derived from the lattice defect of graphitic carbon and is not present in the Raman spectra of well-crystalline graphite.…”

“…[4][5][6][7][8][9] According to Quirico et al [4] and Bonal et al [5] , the maturity of the organic matter in chondritic meteorites, determined by Raman spectroscopy, has been used as a powerful metamorphic tracer. They showed that there were correlations between FWHM-D (D-band width) and the petrologic types determined by induced thermoluminescence, or between I D =I G ratio and the petrologic types.…”