摘要 : We report the first neon isotope measurements on phenocrysts from subaerial and submarine Samoan lavas. These new data complement existing Ne-isotope data from Samoan peridotite xenoliths (Poreda, R.J., Farley, K.A.,1992. Rare gas... 展开 We report the first neon isotope measurements on phenocrysts from subaerial and submarine Samoan lavas. These new data complement existing Ne-isotope data from Samoan peridotite xenoliths (Poreda, R.J., Farley, K.A.,1992. Rare gases in Samoan xenoliths. Earth Planet. Sci. Lett. 113, 689 129-144). Neon isotopes were measured in magmatic phenocrysts separated from nine shield-stage lavas from 5 Samoan volcanoes, including Ofu, Ta'u, Vailulu'u, Malumalu and Savai'i. Phenocrysts from subaerial Samoan lavas have higher ~(20)Ne/~(22)Ne than submarine phenocrysts, which may suggest different atmospheric contamination mechanisms for these two different eruptive environments. Olivine phenocrysts from a subaerial Ta'u lava exhibit the highest ~(20)Ne/~(22)Ne (11.33±0.08, 1σ) value in this study. Two subaerial Samoan samples from Ofu Island with high ~3He/~4He ratios (Ofu-04-06 and Ofu-04-03; 34 and 24 Ra [ratio to atmosphere], respectively) also have elevated ~(20)Ne/~(22)Ne ratios relative to air, and in a three-isotope neon plot the Ofu samples are indistinguishable from measurements made on high ~3He/~4He lavas from Hawaii, Iceland and Galapagos. The similarity of helium and neon isotopes in Ofu and Hawaii-Iceland-Galapagos is remarkable given the distinctions in ~(87)Sr/~(86)Sr (0.70458 for Ofu vs. 0.70329-0.70368 for Hawaii-Iceland-Galapagos) and ~(143)Nd/~(144)Nd (Ofu's 0.51283 vs. 0.51294-0.51297 for Hawaii-Iceland-Galapagos) in high ~3He/~4He lavas from these localities. Thus, the occurrence of similar helium and neon isotope compositions in lavas from these 4 hotspots does not appear to be linked to their variable Sr and Nd isotope compositions, and demonstrates a complex relationship between the isotopes of noble gases and the more refractory radiogenic isotopes. Additionally, we observe strongly nucleogenic neon isotopes in one the most isotopically-enriched (~(87)Sr/~(86)Sr > 0.718) Samoan lavas. This observation is consistent with the presence of recycled, continentally-derived marine sediment in the mantle source of the most enriched lavas from Samoa. 收起