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 (Γ D) 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 Γ D 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.

Organic matter in carbonaceous chondrite lithologies of Almahata Sitta: Incorporation of previously unsampled carbonaceous chondrite lithologies into ureilitic regolith

“…The peak position (ω), the FWHM (Γ), and the peak intensity ratio (I D =I G ) of the D and G bands obtained by peak fitting are shown in Fig. 4 Kiryu et al 2020), AhS 671 was completely off from the trends and large heterogeneity was observed. The absolute intensity of D and G bands of AhS 91A was significantly lower than those of AhS 671 (Fig.…”

“…The peak positions (ω D and ω G ), the full width at half maximum (FWHM, Γ D and Γ G ), and the peak intensity ratio (I D =I G ) of defect (D:~1350 cm −1 ) band and graphite (G:~1590 cm −1 ) band were determined by peak fitting to the Lorentzian and BWF (Breit-Wigner-Fano), respectively-so-called L-BWF model (Ferrari and Robertson 2000)-with a linear baseline correction between 900 and 1800 cm −1 , following the method in Kiryu et al (2020).…”

“…where I L3 is the integrated intensity of Fe 3+ L 3 edge (707.6-709.6 eV), I L2 is the integrated intensity of Fe 2+ L 2 edge (719.0-721.0 eV), a = 0.193, b = -0.465, Kiryu et al (2020). c = 0.366, and x = Fe 3+ /ΣFe.…”

Thermal metamorphism of CM chondrites: A dehydroxylation‐based peak‐temperature thermometer and implications for sample return from asteroids Ryugu and Bennu

“…Many workers observe that T estimated from Raman spectroscopy of IOM in chondrites in general (e.g., Cody et al 2008;Schmidt and Hinrichs 2020) and ATCC chondrites in particular (e.g., Quirico et al 2014;Schmidt and Hinrichs 2020) are significantly (up to~600°C) lower than those estimated from mineralogical and textural parameters. For example, for Y-86720 (metamorphism stage IV of Nakamura [2005], >750°C), Raman spectroscopy yielded estimates of <230°C (Busemann et al 2007), 70°C using an equation for long-duration geological maturation of OM and 245°C using an equation for rapid carbonization of OM (Schmidt and Hinrichs 2020), 496 AE 55°C using an equation for longduration geological maturation of OM (Kiryu et al 2020), and carbon-XANES measurements yielded 265 AE 42°C (Cody et al 2008). Similarly, for WIS 91600 (metamorphism stage II of Nakamura [2005], 300-500°C), Raman spectroscopy yielded estimates of 362.2 AE 49.8°C for matrix IOM (Chan et al 2017), 67°C using an equation for long-duration geological maturation of OM, and 277°C using an equation for rapid carbonization of OM (Schmidt and Hinrichs 2020).…”

“…Temperatures estimated from various spectroscopies of IOM in CM chondrites that experienced only aqueous alteration vary among laboratories by more than 300°C. For example, for Murchison, Raman spectroscopy yielded estimates of <220°C(Busemann et al 2007), 309.2 AE 6.3°C for matrix IOM(Chan et al 2017), 60°C using an equation for long-duration geological maturation of OM and 222°C using an equation for rapid carbonization of OM(Schmidt and Hinrichs 2020), four values using an equation for long-duration geological maturation of OM ranging from 396 AE 47 to 443 AE 51°C(Kiryu et al 2020), and carbon-XANES measurements yielded 96 AE 65°C(Cody et al 2008). Similarly, for Nogoya, AE 15.2°C for matrix IOM…”