近日，日本筑波大学Hironao Matsumoto团队研究了1.43亿年海水锇同位素记录：火山作用与构造作用的趋势、节律与动力学。2026年1月22日出版的《科学》杂志发表了这项成果。

构造事件与火山活动形成的大火成岩省（LIPs）曾改变地球古气候。锇（Os）与锶（Sr）同位素比值是追溯大陆风化历史与大火成岩省喷发活动的关键示踪指标。然而，白垩纪海水锇同位素及河流锇-锶数据的匮乏限制了定量重建研究。

研究组呈现了从白垩纪延续至今的长期锇同位素记录，揭示了白垩纪期间约1000万至2000万年的周期性波动，该周期与大火成岩省的韵律性喷发事件相吻合。海水锇-锶同位素变化趋势显示，晚白垩世（约9000万年前）和古近纪（约3500万年前）大陆风化模式发生转变——前者归因于大西洋张开期间冈瓦纳大陆内部风化作用增强，后者则与喜马拉雅山脉隆升及冰川活动相关。该锇同位素记录凸显了其在示踪长期大火成岩省活动周期及识别重大古地理转折点方面的重要价值。

附：英文原文

Title: 143–million-year seawater osmium isotopic record: Trends, rhythms, and dynamics of volcanism and tectonics

Author: Hironao Matsumoto, Yasuto Watanabe, Rodolfo Coccioni, Fabrizio Frontalini, Toshihiro Yoshimura, Junichiro Kuroda, Katsuhiko Suzuki

Issue&Volume: 2026-01-22

Abstract: Tectonic events and volcanic pulses forming large igneous provinces (LIPs) have altered Earth’s paleoclimate. Osmium (Os) and strontium (Sr) isotopic ratios are key tracers of past continental weathering and LIP eruptions. However, limited Cretaceous seawater Os and riverine Os–Sr data have hindered quantitative reconstructions. In this study, we present a long-term Os isotopic record from the Cretaceous to the present, revealing ~10– to 20–million-year cycles during the Cretaceous that align with rhythmic LIP eruptions. Seawater Os–Sr isotopic trends indicate transitions in continental weathering patterns during the Late Cretaceous [~90 million years ago (Ma)] and Paleogene (~35 Ma) ascribed to intensified weathering of interior Gondwana during the opening of the Atlantic Ocean and the uplift and glaciation of the Himalaya, respectively. Our Os isotopic record highlights its utility in tracing long-term LIP cycles and identifying major paleogeographic turning points.

DOI: adw8301

Source: https://www.science.org/doi/10.1126/science.adw8301