美国伍兹霍尔海洋研究所Horton, F.及其团队近日提出了来自地核最高地球的³He /⁴He可信证据。该项研究成果发表在2023年10月18日出版的《自然》上。

研究人员报道，迄今为止在地球上火成的岩石和 Baffin 岛熔岩中的橄榄石中，所测得的最高岩浆 ³He /⁴He 比(是大气比的 67.2±1.8 倍)。研究人员认为，这些熔岩中极高的 ³He /⁴He 氦可能来自地核。地核假说的可行性放宽了长期以来的限制，该限制基于与全球地幔柱相关的熔岩中的惰性气体（即太阳星云中的自吸积的早期阶段以来，就一直存在于地幔中的挥发性元素）。

据悉，许多与地幔柱有关的熔岩比上部对流地幔具有更高的 ³He /⁴He 比，这一观察结果支持着地球深部的地球物理、地球动力学和地球化学的模型。通常，高的 ³He /⁴He 比被认为是来自太阳星云或在早期行星吸积阶段，融入地球的太阳风辐射的物质。传统意义上来说，这种具 ³He /⁴He 比的成分被认为是地幔固有的，能够避免由巨大撞击和数十亿年的地幔对流引起的除气作用。

附：英文原文

Title: Highest terrestial ³He /⁴He credibly from the core

Author: Horton, F., Asimow, P. D., Farley, K. A., Curtice, J., Kurz, M. D., Blusztajn, J., Biasi, J. A., Boyes, X. M.

Issue&Volume: 2023-10-18

Abstract: The observation that many lavas associated with mantle plumes have higher ³He /⁴He ratios than the upper convecting mantle underpins geophysical, geodynamic and geochemical models of Earth’s deep interior. High ³He /⁴He ratios are thought to derive from the solar nebula or from solar-wind-irradiated material that became incorporated into Earth during early planetary accretion. Traditionally, this high-³He /⁴He component has been considered intrinsic to the mantle, having avoided outgassing caused by giant impacts and billions of years of mantle convection. Here we report the highest magmatic ³He /⁴He ratio(67.2±1.8 times the atmospheric ratio) yet measured in terrestrial igneous rocks, in olivines from Baffin Island lavas. We argue that the extremely high-³He /⁴He helium in these lavas might derive from Earth’s core. The viability of the core hypothesis relaxes the long-standing constraint—based on noble gases in lavas associated with mantle plumes globally—that volatile elements from the solar nebula have survived in the mantle since the early stages of accretion.

DOI: 10.1038/s41586-023-06590-8

Source: https://www.nature.com/articles/s41586-023-06590-8