近日，英国南安普顿大学T. M. Gernon团队揭示了丰富的地幔由大陆根的持续对流侵蚀形成。2025年11月11日出版的《自然—地球科学》杂志发表了这一最新研究成果。

软流圈富地球化学地幔的起源对于理解地球内部的物理、热、化学演化具有重要意义。虽然海洋沉积物和深部地幔柱的俯冲作用与这种富集有关，但它们不能完全解释所观察到的地球化学趋势。

研究组提出了地球动力学模型，表明富集的地幔可以通过高度有组织的对流侵蚀从次大陆岩石圈地幔的根部解放出来，这一过程与大陆裂谷和破裂有关。研究组证明，这种不稳定的对流“链”以一种可预测和可量化的方式，在数千万年的时间里，将丰富的岩石圈物质扫进海底软流圈——对于密度更大、被移除的龙骨来说，这一过程可能更快。

研究组用来自印度洋海山省的地球化学数据测试了这个模型，这是一个近大陆的富集火山活动地点，深地幔柱的影响很小。这一地区显示出富集的地幔火山活动在5000万年的分裂期间达到峰值，随后富集程度稳步下降，与模型预测一致。研究组认为，局部变质的龙骨的持续和长距离的横向运输可以解释位于破碎大陆的海山和海洋岛屿火山数十亿年的富集。大陆板块分裂引发了裂谷后持续很长时间的浅层地幔动力学重组，扰乱了地圈和深层碳循环。

附：英文原文

Title: Enriched mantle generated through persistent convective erosion of continental roots

Author: Gernon, T. M., Brune, S., Hincks, T. K., Palmer, M. R., Spencer, C. J., Watts, E. J., Glerum, A.

Issue&Volume: 2025-11-11

Abstract: The origin of geochemically enriched mantle in the asthenosphere is important to understanding the physical, thermal and chemical evolution of Earth’s interior. While subduction of oceanic sediments and deep mantle plumes have been implicated in this enrichment, they cannot fully explain the observed geochemical trends. Here we use geodynamic models to show that enriched mantle can be liberated from the roots of the subcontinental lithospheric mantle by highly organized convective erosion, a process tied to continental rifting and break-up. We demonstrate that this ‘chain’ of convective instabilities sweeps enriched lithospheric material into the suboceanic asthenosphere, in a predictable and quantifiable manner, over tens of millions of years—potentially faster for denser, removed keels. We test this model using geochemical data from the Indian Ocean Seamount Province, a near-continent site of enriched volcanism with minimal deep mantle plume influence. This region shows a peak in enriched mantle volcanism within 50 million years of break-up followed by a steady decline in enrichment, consistent with model predictions. We propose that persistent and long-distance lateral transport of locally metasomatized, removed keel can explain the billion-year-old enrichments in seamounts and ocean island volcanoes located off fragmented continents. Continental break-up causes a reorganization of shallow mantle dynamics that persists long after rifting, disturbing the geosphere and deep carbon cycle.

DOI: 10.1038/s41561-025-01843-9

Source: https://www.nature.com/articles/s41561-025-01843-9