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岩石学报 2001
Hydrogen isotopic compositions of mantle derived clinopyroxene megacrysts from Hannuoba by ion microprobe: micro scale heterogeneity.
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Abstract:
Hydrogen isotopic compositions of three mantle derived clinopyroxene megacrysts from Cenozoic basalts at Hannuoba have been measured by ion microprobe. Heterogeneity occurs in a single grain, δD variation is up to 60‰ on the scale of 2mm. No correlation exists between δD values and hydrogen contents and chemical compositions are homogeneous, so the hydrogen isotope variations are considered to be inherited from parent magma. We suggest that the δD scatter of the parent magma could be related to D/H fractionations between vapor and melt during magma degassing. Shortly after the formation of clinopyroxene megacrysts, they are brought to the surface by the host magma and underwent quenching.