The CV3.2 carbonaceous chondrite Allende was subjected to an 11-step sequential chemical dissolution using increasingly acidic reagents in order provide information about the phase distribution of the moderately- to highly-volatile halogens Cl, Br, and I.  Halogen concentrations in the resulting solutions were determined using ICPMS.  These elements were found to reside in water-soluble phases, presumably alkali halides, and HNO3 soluble phases, such as feldspar and/or Cl apatite, both theoretically predicted host phases for halogens.  Significantly, all three halogens also show a relatively large release with 0.09 M CH3COOH, a step that in previous experiments has contained a majority of the highly-volatile elements Bi, Tl, In, and Cd.  We interpret these results as the preferential dissolution of surfaces of fine-grained matrix.  Our results are consistent with the theory that these elements are preferentially sited on the surfaces of meteorite matrix material potentially due to secondary processing on the parent body.

Distribution of Cl, Br, and I in the carbonaceous chondrite Allende

243rd National Meeting (2012)

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