Carbonates in Ryugu and Bennu with MicrOmega: Insights into Aqueous Alteration on Primitive AsteroidsOPEN ACCESS 

· by · in , , , ,

Max Mahlke, Cateline Lantz, Cédric Pilorget, Donia Baklouti, Rosario Brunetto, Kentaro Hatakeda, Te Jiang, Damien Loizeau, Rachel Sheppard, Alice Aléon-Toppani, Masanao Abe, Jean-Pierre Bibring, Yuma Enokido, Ryota Fukai, Vincent Hamm, Yuya Hitomi, Seiya Kawasaki, Tania Le Pivert-Jolivet, Akiko Miyazaki, Kana Nagashima, Arisa Nakano, Aiko Nakato, Laura Nardelli, Masahiro Nishimura, Tomoko Ojima, Tatsuaki Okada, François Poulet, Lucie Riu, Ryosuke Sakurai, Rui Tahara, Tomohiro Usui, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Seiichiro Watanabe, Makoto Yoshikawa and Yuichi Tsuda

The Planetary Science Journal, Volume 7, Number 5, Published 19 May 2026

LINK (OPEN ACCESS)
PDF (OPEN ACCESS)

“Aqueous alteration was one of the earliest geological processes in the solar system and significantly shaped the mineralogical diversity observed in primitive minor bodies. Carbonate minerals are reliable tracers of the physicochemical conditions during alteration processes on early planetesimals. We present a comprehensive characterization of carbonates in the returned samples of asteroids Ryugu and Bennu, performed using the MicrOmega near-infrared hyperspectral microscope. We identify two major carbonate species, dolomite (CaMg(CO3)2) and breunnerite ((Mg,Fe)CO3), with similar relative abundances and mean elemental compositions on both asteroids, indicating analogous aqueous alteration pathways on their parent bodies. A general spatial separation of dolomite and breunnerite is observed, indicating that at size scales of 10–100 μm, alteration conditions favored the precipitation of one species over the other. We interpret this as evidence for a spatially heterogeneous local water–rock ratio, suggesting that a high local water–rock ratio suppresses the formation of dolomite, instead favoring precipitation of breunnerites. Based on relative carbonate abundances, we conclude that chambers A (sampling the surface) and C (predominantly sampling the subsurface) of the Ryugu sample contain different mixtures of lithologies with different alteration degrees.”

Related posts (automatically generated):

  1. Mid-infrared emissivity of partially dehydrated asteroid (162173) Ryugu shows strong signs of aqueous alterationOPEN ACCESS 
  2. Apatite in Bennu samples indicates multiple stages of aqueous alterationOPEN ACCESS 
  3. A window into the early stages of aqueous alteration from mackinawite in samples of asteroid BennuOPEN ACCESS 
  4. Three-dimensional textures of Ryugu samples and their implications for the evolution of aqueous alteration in the Ryugu parent body
  5. Prebiotic organic compounds in samples of asteroid Bennu indicate heterogeneous aqueous alterationOPEN ACCESS 
  6. Abundant supernova dust and heterogeneous aqueous alteration revealed by stardust in two lithologies of asteroid BennuOPEN ACCESS 
  7. Early fluid activity on Ryugu inferred by isotopic analyses of carbonates and magnetite
  8. Bright carbonate veins on asteroid (101955) Bennu: Implications for aqueous alteration history
  9. Pyrrhotites in asteroid 162173 Ryugu: Records of the initial changes on their surfaces with aqueous alterationOPEN ACCESS 
  10. Primordial aqueous alteration recorded in water-soluble organic molecules from the carbonaceous asteroid (162173) RyuguOPEN ACCESS 
Tags: , , , , , ,