Kinetics in thermal evolution of Raman spectra of chondritic organic matter to evaluate thermal history of their parent bodies

Abstract In order to establish kinetic expressions for Raman spectroscopic parameters of organic matter in chondritic meteorites with heating, a series of heating experiments (at 600–900 °C for 3–48 h) of the Murchison (CM2) meteorite was conducted. For comparison, several carbonaceous chondrites with various metamorphic degrees—Allende (CV3.2), Moss (CO3.6), Yamato (Y‐) 793321 (heated CM2), and Tagish Lake (ungrouped C2)—were also analyzed by the Raman spectrometer. Changes in the full width at half maximum of the D1 band (ΓD) of heated Murchison correlated well with temperature and time, and showed similar trends of chondrites with various metamorphic degrees. We obtained the kinetic expressions for the changes in ΓD by heating to estimate the time–temperature history of thermally metamorphosed type 3 chondrites and heated CM chondrites. Our results may also be useful for asteroids which are the targets of Hayabusa2 and OSIRIS‐REx missions.