Iodine‐xenon studies of Bjurböle and Parnallee using RELAX

Iodine‐xenon analyses of chondrules from the Bjurböle L4 and Parnallee LL3.6 meteorites have been made using a continuous wave laser microprobe and the resonance ionisation mass spectrometer RELAX. The excess 129 Xe content released from the Bjurböle chondrule is lower than previous stepped‐heating studies have found, suggesting that the technique does not completely degas the samples. Nonetheless, clear isochrons were produced, and data for initial 129 Xe/ 130 Xe are consistent with earlier work. A correlation is evident in each chondrule between 131 Xe * and 128 Xe * perhaps indicating a common host‐phase for their parent nuclides, a condition possibly fulfilled by a Te‐ and I‐bearing sulfide. The I‐Xe system of a Parnallee macrochondrule exhibits no excess 129 Xe, possibly as a result of thermal alteration or deformation before accumulation of the meteorite. A cristobalite‐bearing chondrule depleted in 16 O yields an I‐Xe age of 4.5 ± 0.5 Ma after the mean Bjurböle age.