当前位置: X-MOL 学术Nat. Geosci. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Potassium isotopic evidence for recycling of surface water into the mantle transition zone
Nature Geoscience ( IF 18.3 ) Pub Date : 2024-05-14 , DOI: 10.1038/s41561-024-01452-y
Kai-Chen Xing , Feng Wang , Fang-Zhen Teng , Wen-Liang Xu , Yi-Ni Wang , De-Bin Yang , Hong-Lin Li , Yan-Chao Wang

Global water cycling involves interactions between Earth’s interior and its surface environment. Geophysical and mineral physics studies have suggested that the mantle transition zone is hydrous, at least locally. However, there are poor constraints on whether water in the transition zone is sourced internally from primordial materials or from Earth’s surface via subduction-related processes. Cenozoic volcanism in Northeast Asia is triggered by hot and wet upwelling flows above the stagnated Pacific slab and has produced mantle transition zone-derived volcanic rocks. Potassium behaves geochemically similarly to water during magmatic processes, and hence can potentially be used to constrain the nature of water in the mantle transition zone. Here we report potassium isotopes in a set of well-characterized Cenozoic volcanic rocks in Northeast Asia. Their K isotope ratios (−0.83‰ to −0.36‰) are lower than primitive mantle (−0.42‰ ± 0.08‰), suggesting crustal potassium inputs and modifications of the mantle transition zone by subducted slab materials. Decoupling of potassium isotopes from radiogenic Sr–Nd–Pb isotopes, combined with a geophysically identified low-resistivity anomaly above the transition zone, requires the input of surficial water from the stagnated subducted slab into the transition zone. This water can then be cycled back to the surface in Northeast Asian volcanics.



中文翻译:

地表水循环进入地幔过渡带的钾同位素证据

全球水循环涉及地球内部与其表面环境之间的相互作用。地球物理和矿物物理研究表明,地幔过渡带至少在局部地区是含水的。然而,对于过渡带中的水是来自内部原始物质还是来自地球表面通过俯冲相关过程的限制很少。东北亚新生代火山活动是由停滞的太平洋板片上方的热湿上升流引发的,并产生了地幔过渡带衍生的火山岩。钾在岩浆过程中的地球化学行为与水相似,因此可用于限制地幔过渡带中水的性质。在这里,我们报告了东北亚一组特征明确的新生代火山岩中的钾同位素。它们的钾同位素比(−0.83‰至−0.36‰)低于原始地幔(−0.42‰±0.08‰),表明地壳钾输入和俯冲板片物质对地幔过渡带的改造。钾同位素与放射性 Sr-Nd-Pb 同位素的解耦,加上地球物理上识别出的过渡带上方的低电阻率异常,需要将地表水从停滞的俯冲板片输入到过渡带。然后这些水可以在东北亚火山中循环回到地表。

更新日期:2024-05-14
down
wechat
bug