²⁶Al in cores of the Keyes chondrite

Abstract

Cosmogenic 26Al was measured in six samples from two cores of the Keyes chondrite, previously analyzed for spallogenic 3He, 21Ne, and 38Ar. Specific activities varied from 68.9 ± 5.4 dpm/kg near the center (depth, ∼30 cm) to 50.9 ± 3.7 near the postatmospheric surface (depth, ∼3 cm). The data are consistent with an approximately linear decrease in 26Al activity with radial distance r from the center of Keyes: (26Al)obs/(26Al)calc = 1.04 (±0.05) − 0.0104 (±0.0032)(r). The measured 26Al (dpm/kg)/21Ne(10−8 cm3/g) ratio is constant at 6.13 ± 0.18 for the six samples, corresponding to an average atomic production ratio of 0.222 for the meteorite.