Earliest Evidence of Nebular Shock Waves Recorded in a Calcium-Aluminum-rich Inclusion

Prajkta Mane, Shawn Wallace, Maitrayee Bose, Paul Wallace, Meenakshi Wadhwa, Juliane Weber, Thomas J. Zega

Geochimica et Cosmochimica Acta
Available online 20 June 2022



• Electron backscatter diffraction analysis of a calcium-aluminum rich inclusion from a primitive meteorite shows extensive deformation features.
• The surrounding rim sequence records lesser degree of deformation.
• The 26Al-26Mg chronology data of the CAI and its rim sequence suggests that the major deformation event occurred early, within a few hundred thousand years after the CAI formation.
• Nebular shocks similar to those responsible for chondrule formation may have caused this observed deformation in the CAI.
• Our results imply that nebular shock events could have been active over a larger temporal and spatial scale in the solar protoplanetary disk than previously recognized.”

“Calcium-aluminum-rich inclusions (CAIs) and chondrules are among the most predominant chondritic components contained within primitive meteorites. As CAIs are the first solids to form in the solar nebula, they contain a record of its earliest chemical and physical processes. Here we combine electron backscatter diffraction (EBSD) and 26Al-26Mg chronology techniques to determine the crystallographic properties and ages of CAI components that provide temporal as well as spatial constraints on their origins and subsequent processing in the solar protoplanetary disk. We find evidence of shock deformation within a CAI, suggesting that it was deformed as a free-floating object soon after the CAI formation at the beginning of the Solar System. Our results suggest that even though CAIs and chondrules formed in distinct environments and on different timescales, they were likely affected by similar shock processes that operated over large temporal (0 to ∼4 Ma) and spatial (0.2 to at least 2 to 3 au) extents. Our results imply that nebular shock events were active on a wider scale in the solar protoplanetary disk than previously recognized.”