Comparison of micro-spectroscopic signatures of 2 peculiar CM-type meteorites: Asuka 12236 and Paris.

In this study we compare the infrared and Raman micro-spectroscopy signatures of the Asuka 12236 and Paris meteorite, both considered among the most primitive in the carbonaceous chondrites collection.

The obtained average spectrum from the mid to far infrared of Asuka 12236 reveals the presence of anhydrous minerals as well as a possible contribution of amorphous silicates. Aromatic primary amines and imines heterogeneously distributed within Asuka 12236 are also reported. These components are not found in the average spectrum of Paris.

The richness of Asuka 12236 in nitrogen bearing components, could give clues to its parent’s body. It could originate from regions at large heliocentric distances where the bodies are known to be nitrogen-rich.

In addition, the D and G Raman bands of the two meteorites clearly show that the aromatic carbons of Asuka 12236 are less structured than those of Paris, suggesting thus different thermal histories for the two meteorites.

All our results confirm that Asuka 12236 is an exceptional meteorite, more primitive than Paris. The two CM chondrites should be compared to the pristine extraterrestrial materials returned to Earth by the space missions such as Ryugu (Hayabusa 2) and Bennu (OSIRIS-Rex) even if they are CI’s like.