Consistent ³He/⁴He ratios have been measured for >25 years in geothermal fluids and gases from Cumbre Vieja, La Palma (9.4 ± 0.1R_A, where R_A is the ³He/⁴He of air), and Teide, Tenerife (6.8 ± 0.3R_A), Canary Islands. Both locations are characterized by similar CO₂/³He (∼2 to 4 × 10⁹), mantle-like δ¹³C (−3.3‰ to −4.4‰) and CO₂ output (0.1–0.2 × 10¹⁰ mol yr^–1). Helium isotopic differences between the islands cannot be explained by differential aging and ⁴He ingrowth in their mantle sources. Instead, distinct He reservoirs exist, with a high-μ (HIMU)–type mantle source for La Palma and a more enriched mantle, with possible lithospheric mantle influence, for Tenerife. Geothermal samples from the Canary Islands record a present-day He distribution distinct from higher ³He/⁴He in olivine from older eastern Canary Island lavas, indicating temporal variability in sources. Comparison of geothermal sample data versus olivine, pyroxene, and glass He isotope data for the Canary Islands, Azores, Cape Verde, Hawaiian islands, and Iceland reveals generally good correspondence, even across >1 m.y. of stratigraphy. However, in addition to the Canary Islands, there are examples of inter-island heterogeneity for He isotopes at Hawaii, the Azores, and within Iceland, preserved in hydrothermal samples, minerals, and glasses. In particular, in northwest Iceland, olivine separates from older lavas preserve higher ³He/⁴He than present-day geothermal samples from the same region. This difference likely reflects a reduced mantle-derived ³He input to Icelandic magmatism since the Miocene. Temporal variability in ³He/⁴He, assessed using geothermal and geological materials in conjunction, offers a powerful tool for examining heterogeneity and temporal evolution of mantle sources at intraplate volcanoes.

中文翻译：

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加纳利群岛和其他海洋岛屿中来自地幔的异质氦同位素

在La Palma的Cumbre Vieja（9.4±0.1R _A，其中R _A是空气的³ He / ⁴ He）和地热（Teerife）_的地热流体和气体中，一致的³ He / ⁴ He比率已被测量超过25年。（6.8±0.3R _A），加那利群岛。这两个位置的特征在于相似的CO ₂ / ³赫（〜2至4×10 ⁹），套状的δ ¹³ C（-3.3‰至-4.4‰）和CO ₂输出（0.1-0.2×10 ¹⁰摩尔年^{- 1}）。孤岛之间的氦同位素差异无法通过年龄差异和⁴来解释。他向内生长在他们的地幔来源中。取而代之的是，存在着独特的He储层，其中La Palma具有高μ（HIMU）型地幔源，特内里费岛则具有更富集的地幔，可能受到岩石圈地幔的影响。来自加那利群岛的地热样品记录了当今的He分布，与较高的³ He / ⁴截然不同他来自东部加那利群岛东部较古老的熔岩的橄榄石中，表明来源的时间变化。加纳利群岛，亚速尔群岛，佛得角，夏威夷群岛和冰岛的地热样品数据与橄榄石，辉石和玻璃的He同位素数据相比，即使在> 1 my的地层上也显示出良好的对应关系。但是，除了加那利群岛外，还有夏威夷，亚速尔群岛和冰岛内部氦同位素的岛间异质性实例，这些均保存在热液样品，矿物质和玻璃中。特别是，在冰岛西北部，与较早的熔岩分离的橄榄石保留的³ He / ⁴ He高于当前来自同一地区的地热样品。这种差异可能反映出减少的地幔源³自中新世以来，他开始从事冰岛岩浆活动。结合地热和地质材料评估的³ He / ⁴ He的时间变异性，为检验板内火山地幔源的异质性和时间演化提供了有力的工具。