Source Materials for North American Tektites

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Conference Abstract

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We have previously reported the elemental and isotopic compositions of all noble gases in several tektite samples from Bedias, Texas. However, these experiments had relatively high Kr and Xe blank levels compared to sample concentrations. Special efforts have been made to reduce instrument blank levels to ~50%of the Kr and Xe signals obtained from tektite samples. Under these relatively low blank conditions we have measured the noble gas abundances in three bediasites and two georgiaites. Prior to this study there existed only one heavy noble gas measurement on North American tektites. For comparison, an Ivory Coast tektite has also been measured. The abundances and isotopic compositions of all the noble gases in these tektites are reported and compared with tektites from other strewn fields. Important findings of this study are enormous enrichments of Ne relative to Ar and progressive enhancements of Kr and Xe relative to Ar (all data normalized to air ratios). This noble gas fractionation pattern seems to be a common feature of shales and sedimentary rock material, and thus may provide clues as to the source materials from which the North American tektites were created by impact.


Physics and Astronomy