20-EPN2-072: Dynamics of the early inner solar system inferred from combined 26 Al-26 Mg and Cr–Ti–O isotope systematics of non-carbonaceous chondrules
Visit by Christian Jansen, WWU Münster (Germany) to TA2.9 Ion Probe Facility (IPF), CRPG (France).
Dates of visit: 03-12 August 2022
Report Summary: The advent of non-traditional isotopic systems (e.g., Ti, Cr, Mo) revealed that chondrites—the most primitive witnesses of the early solar system—display a fundamental isotopic dichotomy, with carbonaceous chondrites (CCs) showing large nucleosynthetic anomalies relative to terrestrial standards that are not observed in non-carbonaceous chondrites (NCs). NC and CC reservoirs may thus represent the primordial inner and outer parts of the solar system, respectively.
The scientific goal of this project is to combine several isotopic systems (O, Ti, Cr) for deciphering the conditions and chronology of chondrule formation in the NC reservoir. A key parameter of this approach is to also have access to the formation ages of these chondrules. This requires in situ measurements with a secondary ion mass spectrometer for determining the 26Al ages of chondrule crystallisation.
To do so, 16 chondrules were separated from the minimally altered ordinary chondrite NWA 5206. They were split into two pieces for determining their (i) Cr and Ti isotopic compositions (bulk measurements) and (ii) O isotopic compositions and 26Al ages. These chondrules show no 54Cr or 50Ti excesses and classical oxygen isotopic composition (with ∆17 O ranging from -1 to + 1 ‰). 26Al ages are coherent with previous estimates showing that NC chondrules formed over several million years during the evolution of the inner disk.