The University of Arizona

Distribution of noble gases in Chinese tektites: Implications for neon solubility in natural gases

D. L. PINTI, T. MATSUMOTO, J. I. MATUSDA, Z. FANG

Abstract


Five indochinites from Hainan Island and the Leizhou Peninsula, China were analyzed for noble gas abundances and isotopic ratios. These splash-form tektites show vesiculation ranging from 0.4 vol% to 8 vol%, as determined by digital image analysis (software SXM®) on thin section photographs. To study the distribution of noble gases in vesicles and in glass, the gases were extracted by heating and by crushing, respectively, on 2 aliquots of the same sample. The results show that 5 to 53% of the total measured 20Ne resides in vesicles. The calculated concentration of neon dissolved in the glass is higher (0.7-1 x 10^(-7) cm3STP/g) than that expected from solubility equilibrium (1 10^(-8) cm3STP/g), assuming solubility data from MORB glasses. The neon concentration of splash-form tektites, those analyzed in this work and those from other strewn-fields worldwide, is correlated with the SiO2 content of glass and with the nonbridging oxygen per tetrahedral cation in the melt (hereafter NBO/T ratio), the latter being an index of the free-volume in the silica network where neon could be dissolved. These correlations suggest that the glass structure of tektite has a larger free-volume available for dissolving noble gases than MORB glasses.

Keywords


Neon;Tektites;Noble gases solubility

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