- Names
-
- E. Quirico
- H. Yabuta
- P. Beck
- L. Bonal
- L. Nittler
- C.M.O'D. Alexander
- Title
- Compositional heterogeneity of insoluble organic matter extracted from asteroid Ryugu samples
- Abstract
- Short-duration heated chondrites form a significant population among the primitive carbonaceous chondrites. The origin of this heating process is usually attributed to either impact or solar heating. Shock recovery experiments performed on carbonaceous chondrites have revealed typical evolution in the petrography and mineralogical composition of these objects, but no study has focused on the chemical and structural transformations of insoluble organic matter (IOM). We report on shock recovery experiments designed to characterize the composition and structure of IOM along with dehydration. Murchison experiments show carbonization of IOM at all shock intensities (5-40 GPa) and a pronounced structural evolution at 40 GPa associated with complete dehydroxylation of serpentines, olivine and glass formation. The dD isotopic composition of IOM evolves significantly, with the rapid disappearance of hot spots and a bulk dD of -79‰ at 40 GPa. These experiments only partially reproduce the characteristics of natural samples. At 40 GPa the dehydroxylation is consistent with stage III heated chondrites, but the structural characteristics of the IOM suggest a stage I, i.e. a slight modification of the IOM in a matrix dominated by serpentines. The isotopic characteristics at 40 GPa are incompatible with chondrite values. These results suggest that the IOM evolution in short-duration heated chondrites is essentially controlled by the post-shock cooling episode, which lasts from hours to years, compared to < 1s for the shock peak pressure. In this respect, the IOM evolution during short-duration heating is better simulated by heating experiments under controlled redox conditions. Experiments performed on EET 90628 show a structural evolution consistent with natural objects. In particular, the co-evolution of the width and position of the D-band (FWHM-D and ID/IG, respectively) in the Raman spectra of the shocked samples is consistent with those measured on series of Type 3 chondrites. However, as observed in the case of Murchison, a substantial increase in IOM structural order is not achieved with shock experiments. An interesting finding is that the G-band width and position parameters (FWHM-G and wG) do not correlate with the shock intensity, just as these parameters do not correlate with the intensity of thermal metamorphism in the case of Type 3 chondrites, which is not observed on Earth in the case of coals and kerogens that experienced a progressive thermal history. This suggests that the structural characteristics of the IOM of Type 3 chondrites are controlled not only by the intensity of radiogenic metamorphism, but also by impacts.
- Keywords
- spectroscopy, transmission, absorbance spectra, band position, mid-IR, organic matter, IOM, chondrite, Raman
- Content
- spectral data, planetary sciences
- Year
- 2025
- Journal
- Meteoritics and Planetary Science
- Document type
- article
- Publication state
- submitted
- Experiment/Spectra
-
- Normalized and baseline-corrected mid-IR absorbance spectrum of matrix fragment from unshocked Murchison
- Normalized and baseline-corrected mid-IR absorbance spectrum of matrix fragment from unshocked Murchison
- Normalized and baseline-corrected mid-IR absorbance spectrum of matrix fragment from Murchison shocked at 5 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of matrix fragment from Murchison shocked at 10 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of matrix fragment from Murchison shocked at 20 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of matrix fragment from Murchison shocked at 40 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from unshocked Murchison
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from Murchison shocked at 5 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from Murchison shocked at 10 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from Murchison shocked at 20 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from Murchison shocked at 20 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from Murchison shocked at 40 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from Murchison shocked at 50 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from Murchison shocked at 50 GPa
- Normalized and baseline-corrected mid-IR absorbance spectrum of IOM extracted from Murchison shocked at 50 GPa
- Raw Raman spectra (514 nm laser) of IOM extracted from unshocked Murchison
- Raw Raman spectra (514 nm laser) of IOM extracted from unshocked Murchison
- Raw Raman spectra (514 nm laser) of IOM extracted from Murchison shocked at 5 GPa
- Raw Raman spectra (514 nm laser) of IOM extracted from Murchison shocked at 10 GPa
- Raw Raman spectra (514 nm laser) of IOM extracted from Murchison shocked at 20 GPa
- Raw Raman spectra (514 nm laser) of IOM extracted from Murchison shocked at 40 GPa
- Baseline-corrected Raman spectra (514 nm laser) of IOM extracted from unshoked Murchison
- Baseline-corrected Raman spectra (514 nm laser) of IOM extracted from unshoked Murchison
- Baseline-corrected Raman spectra (514 nm laser) of IOM extracted from Murchison shocked at 5 GPa
- Baseline-corrected Raman spectra (514 nm laser) of IOM extracted from Murchison shocked at 10 GPa
- Baseline-corrected Raman spectra (514 nm laser) of IOM extracted from Murchison shocked at 20 GPa
- Baseline-corrected Raman spectra (514 nm laser) of IOM extracted from Murchison shocked at 40 GPa
- Raw Raman spectra (514 nm laser) of matrix fragments from EET90628 (L3) shocked at 5 GPa
- Raw Raman spectra (514 nm laser) of matrix fragments from EET90628 (L3) shocked at 10 GPa
- Raw Raman spectra (514 nm laser) of matrix fragments from EET90628 (L3) shocked at 20 GPa
- Raw Raman spectra (514 nm laser) of matrix fragments from EET90628 (L3) shocked at 30 GPa
- Raw Raman spectra (514 nm laser) of matrix fragments from EET90628 (L3) shocked at 40 GPa
- Raw Raman spectra (514 nm laser) of matrix fragments from EET90628 (L3) shocked at 50 GPa