Discovery of primitive CO-bearing fluid in an aqueously altered carbonaceous chondrite.

Water is abundant as solid ice in the solar system and plays important roles in its evolution. Water is preserved in carbonaceous chondrites as hydroxyl and/or HO molecules in hydrous minerals, but has not been found as liquid. To uncover such liquid, we performed synchrotron-based x-ray computed nanotomography and transmission electron microscopy with a cryo-stage of the aqueously altered carbonaceous chondrite Sutter's Mill. We discovered CO-bearing fluid (CO/HO > ~0.15) in a nanosized inclusion incorporated into a calcite crystal, appearing as CO ice and/or CO hydrate at 173 K. This is direct evidence of dynamic evolution of the solar system, requiring the Sutter's Mill's parent body to have formed outside the CO snow line and later transportation to the inner solar system because of Jupiter's orbital instability.