Laser microprobe noble gases and nitrogen analysis of chondrules from the Dhajala chondrite

Ramakant R. Mahajan

Meteoritics & Planetary Science
Version of Record online:08 September 2020


“Noble gases and nitrogen are investigated in eight individual chondrules of the Dhajala H3.8 chondrite. The mean cosmic ray exposure age of the chondrules using 21Ne and 38Ar is 5.9 ± 3.0 Ma. There is no significant evidence of a pre‐exposure for these chondrules. All the measured chondrules contain variable amounts of radiogenic 129Xe. Noble gas analysis indicates Q‐type gas incorporated in the chondrules. The chondrules have variable amounts of N2. The chondrules have distinct trapped N isotopic composition (δ15Nt varies from −24.1 ± 8.4‰ to 89.1 ± 12.7‰), which is inconsistent with Q‐gas and solar wind. These inconsistencies can be considered preliminary evidence in support of multiple trapped components in the chondrules. A heavy N signature component is observed in the chondrules studied contrasted with the solar wind composition. There is no correlation between the concentration of N2 and noble gases. Derivations of variable nitrogen observed in Dhajala (H3.8) chondrules reflect the gas captured at the time of formation, having heterogeneous isotopic signature in the nebula.”