近日，瑞士日内瓦大学教授Sébastien Castelltort团队报道了锂同位素揭示古新世北美风化通量增强始新世热最大值。2025年12月11日出版的《地质学》杂志发表了这项成果。

硅酸盐风化通过吸收大气二氧化碳调控地球长期气候。理解风化机制与速率的变化是预测气候响应时间尺度的关键。

研究组针对古新世-始新世极热事件（PETM）时期，探究了北美“源-汇”系统的反应性及化学风化机制。通过测量墨西哥湾深海沉积岩芯中碎屑锂同位素组成（δ⁷Li）以追踪黏土矿物形成变化，并结合钕同位素（ε_Nd）数据约束沉积物来源。

研究发现，在PETM主体阶段存在一个缓冲的δ⁷Li负偏，可能反映了来自大陆洪泛区的新生黏土与再改造黏土的混合；随后在气候恢复期出现更显著的δ⁷Li负偏。这一模式与美国怀俄明州大陆性比格霍恩盆地的δ⁷Li记录吻合，表明增强的风化与侵蚀通量对PETM事件做出快速响应，进而促进了大气二氧化碳的高效消耗。

附：英文原文

Title: Lithium isotopes reveal enhanced weathering fluxes in North America during the PaleoceneEocene Thermal Maximum

Author: Rocio Jaimes-Gutierrez, Lucas Vimpere, David J. Wilson, Patrick Blaser, Philip A.E. Pogge von Strandmann, Thierry Adatte, Swapan Sahoo, Sébastien Castelltort

Issue&Volume: 2025-12-11

Abstract: Silicate weathering regulates Earth’s long-term climate by removing atmospheric CO2. Understanding changes in weathering regimes and rates is key to predicting climate response time scales. We investigated the reactivity of the North American source-to-sink system and the chemical weathering regime during the PaleoceneEocene Thermal Maximum (PETM). We measured the detrital lithium isotope composition (δ7Li) in a deep-marine sediment core from the Gulf of Mexico, tracking changes in the formation of clay minerals, alongside neodymium isotopes (εNd), to constrain sediment provenance. We find a buffered negative δ7Li excursion during the PETM body, likely reflecting the mixing of neoformed and reworked clays from continental floodplains, followed by a stronger negative δ7Li excursion during the recovery phase. This pattern aligns with the continental Bighorn Basin (Wyoming, USA) δ7Li record, indicating rapid propagation of enhanced weathering and erosion fluxes in response to the PETM, which would have contributed to efficient CO2 drawdown.

DOI: 10.1130/G53708.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G53708.1/723155/Lithium-isotopes-reveal-enhanced-weathering-fluxes