Spectroscopy of carbonaceous chondrites:

Insight into aqueous alteration and thermal metamorphism of asteroids

My thesis project involves using the infrared (IR) spectrum to analyze carbonaceous chondrites (CCs) in order to understand the aqueous alteration and metamorphism process in C-Complex asteroids.

For the purpose of constraining the composition and differentiation history of planetary reservoirs, the chondritic meteorites is a crucial point of reference in Earth and planetary sciences.

Carbonaceous Chondrites

First, I carefully investigated the near-infrared (NIR) spectral feature of Aliphatic organics on asteroids, and link this feature with the heating experiment of carbonaceous materials. At present, I am independently working on linking NIR and mid-infrared spectral features to aqueous alteration and thermal metamorphism process through different CCs and heating experiment data. For example, the spectral in 9-14 and 15 - 25 μm indicate the silicates proportion in CCs: with the alteration degree increase, anhydrous silicates are converted into phyllosilicates (clay), while the 12.4 μm/11.4 μm albedo ratio decreases and the spectral peak shifts toward the short-wave direction.

I hope to use this signature in the future with more MIR IR observations to speculate on the extent of water erosion and thermal metamorphism of main belt asteroids, or to find the parent body of more CCs.

NIR-MIR region spectral variation

Infrared spectroscopy is an important tool for understanding the composition of meteorites and asteroids. There have been many studies in the past in the VNIR region, including the 0.7 μm band, the 2.3 μm band, and most notably the 3 μm band, but unfortunately many of the features are fraught with controversy.The MIR region, which responds to the diagnostic signals of silicate minerals, can provide us with valuable information that may in the future provide us with new avenues for astronomical observation of asteroids and understanding of their evolutionary history.

Potential link with asteroids

The surface mineralogy of asteroids is generally inferred from visible and near-IR reflectance spectra. Comparisons of Observation and CCs based on the 3 μm bands suggest that we need new mechanisms to explain the spectral characteristics of asteroids, and that the parent asteroids of CI meteorites may commonly undergo thermal metamorphic processes.

Aqueous alteration

The aueous alteration likely occurred on a CC parent body at temperatures of ~150℃ within the first ~15 Ma at the early Solar system. Thus, CCs play a vital role in the delivery of volatiles and organic compounds to early Earth. However, these characteristics may not be preserved during prolonged aqueous alteration and subsequent processes such as thermal metamorphism. Because of this, we need to know more about the spectral characteristics of aqueous alteration and thermal metamorphism of meteorites and asteroids

You can find more information in the publication, and please do not hesitate to contact me with questions or interest 😉!

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