Understanding the Origin and Evolution of Meteoritic Refractory Minerals Through Transmission Electron Microscopy

Abstract

Carbonaceous chondrite meteorites contain mmto cm-sized objects called calcium-aluminum-rich inclusions (CAIs) [1]. Based on isotopic age dating and thermodynamic predictions, their refractory mineral components are widely accepted to be the first formed solids in the solar protoplanetary disk [24]. CAIs are acknowledged to have formed initially via gas-phase condensation some 4.56 billion years ago, but many inclusions are known to have experienced subsequent thermal and aqueous processing in the solar nebula and on their parent asteroidal bodies [5]. The structure and chemistry of CAIs record the environments under which they formed and to which they were subsequently exposed. Analytical techniques with high spatial resolution are necessary to determine their structure and chemistry and gain insight into their formation and secondary processing. Thus, transmission electron microscopy can provide valuable information on CAI origins and insight into the earliest processes in our solar system.