美国卡内基科学研究所Jian-Hua Wang团队揭示了地幔过渡带水引发岩石圈减弱和扩张。相关论文于2025年3月10日发表在《地质学》杂志上。

水（氢）通过调节地球内部的各种性质和过程，对地球的地球化学和动态演化至关重要，这些性质和过程控制着分化、板块构造和火山活动。水加入也有望促进岩石圈根部的减薄和移除，因为水可以显著降低岩石圈地幔的粘度。虽然深水的来源存在争议，但最近的证据表明，挥发物可能的储层是地幔过渡带（MTZ），可以在大洋中裂谷系统取样。

地球物理和地球化学证据共同表明，南海（SCS）的火山活动是俯冲板块与MTZ相互作用的结果，使其成为帮助解决这一难题的理想地点。研究组提供了来自SCS样品的玻璃和熔体包裹体的数据，这些样品具有高H₂O/Ce（≈248−649，远高于全球大洋中脊玄武岩值）。这些数据，再加上南海高度不相容元素的消耗增加和低氧逸度，与MTZ中俯冲蛇纹化地幔的存在是一致的，该地幔后来在地幔上升流期间被再循环，引发了岩石圈减薄和裂谷作用。源自MTZ的水可能是地球早期地幔最初水合作用的原因，可能有助于板块构造的发展和维持。

附：英文原文

Title: Mantle transition zone water triggers lithospheric weakening and spreading

Author: Sheng-Ping Qian, Esteban Gazel, Jian-Hua Wang

Issue&Volume: 2025-03-10

Abstract: Water (hydrogen) is crucial to the geochemical and dynamic evolution of Earth by modulating a variety of Earth’s interior properties and processes, which govern differentiation, plate tectonics, and volcanism. Water addition is also expected to promote thinning and removal of lithosphere roots, as water can markedly decrease the viscosity of the lithospheric mantle. While the source of deep water is controversial, recent evidence suggests that a possible reservoir for volatiles is the mantle transition zone (MTZ) that can be sampled at the mid-ocean rift system. Geophysical and geochemical evidence collectively suggests that volcanism in the South China Sea (SCS) resulted from the interaction of the subducting slabs with the MTZ, making it an ideal location to help solve this puzzle. We present data of glasses and melt inclusions from SCS samples with high H2O/Ce (～248649, considerably higher than global mid-ocean ridge basalt values). These data, combined with increased depletion in highly incompatible elements and low oxygen fugacity in the SCS, are consistent with the presence of subducted serpentinized mantle in the MTZ, which was later recycled during mantle upwelling and triggered lithospheric thinning and rifting. Water originating from the MTZ was likely responsible for the initial hydration of the upper mantle during early Earth’s history, potentially facilitating the development and maintenance of plate tectonics.

DOI: 10.1130/G52804.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52804.1/652709/Mantle-transition-zone-water-triggers-lithospheric