A primordial solar-neon enriched component in the source of EM-I-type ocean island basalts from the Pitcairn Seamounts, Polynesia

In contrast to neon, there is no apparent correlation between helium isotope compositions and radiogenic isotopes in the Pitcairn Seamount samples. Positive correlations are observed, however, between ratios of observed 4He to nucleogenic 21Ne (21Nen) against the total helium concentrations and MgO contents, suggesting that preferential loss of mantle helium has occurred, possibly by interaction with seawater during assimilation-fractional crystallization processes. This observation provides a cautionary note for the interpretation of helium isotope results from other oceanic basalt suites.