中国科学院南京古生物所陈吉涛团队，为研究晚古生代冰期开始时全球碳循环模式提供了锌同位素的视角。2024年10月21日，国际知名学术期刊《地质学》发表了这一成果。

据介绍，晚古生代冰期的开始与一个大的全球碳循环扰动（以Tournaisian中期碳同位素偏移[TICE]为代表）相吻合，尽管这一同位素事件的潜在原因仍然不确定。锌（Zn）是浮游生物必需的微量营养素，其同位素组成（δ⁶⁶Zn）在海水中对海洋碳(C)循环的细微波动非常敏感。

研究人员对中国南方两个间距较远的剖面的碳酸盐岩δ⁶⁶Zn-δ¹³C和有机δ¹³C进行了测定，以探讨TICE期间的碳循环。这些记录揭示了δ⁶⁶Zn和δ¹³C在约4m.y上的耦合关系。数据以两个正偏移（峰I和峰II）的形式出现的间隔，中间有一个负偏移（峰间）。

峰值I被归因于海洋初级生产力（MPP）的升高，这是由微量营养素供应增加所刺激的，与硅酸盐风化和/或上升流增强相关。峰间可能记录了冰期海平面下降暴露的大陆架中，再活化有机质的氧化作用，反过来又促进了MPP的再次发生并导致了峰II的出现。因此，TICE记录了复杂的气候碳循环反馈，这可能引起大规模的有机碳埋藏和逐步冷却，标志着持续的晚古生代冰期气候的开始。

附：英文原文

Title: Zinc isotope perspective on global carbon cycling during the onset of the late Paleozoic icehouse

Author: Yutian Zhong, Jitao Chen, Sheng-Ao Liu, Chengshuai Yuan, Biao Gao, Terry T. Isson, Thomas J. Algeo, Qingyi Sheng, Bo Chen, Genming Luo, Xiang-dong Wang, Wenkun Qie

Issue&Volume: 2024-10-21

Abstract: The onset of the late Paleozoic icehouse coincided with a large global carbon-cycle perturbation (represented by the mid-Tournaisian carbon isotope excursion [TICE]), although the underlying cause of this isotopic event remains uncertain. Zinc (Zn), an essential micronutrient for plankton, has an isotopic composition (δ⁶⁶Zn) in seawater that is sensitive to subtle fluctuations in marine carbon (C) cycling. Here, we investigated C cycling during the TICE using paired carbonate δ⁶⁶Zn-δ¹³C and organic δ¹³C records from two widely spaced sections in South China. These records reveal coupling between δ⁶⁶Zn and δ¹³C over an ～4 m.y. interval in the form of two positive excursions (Peaks I and II) separated by a negative shift (interpeak). Peak I is attributed to enhanced marine primary productivity (MPP), which was stimulated by increased micronutrient supply linked to enhanced silicate weathering and/or upwelling. The interpeak may record oxidation of remobilized organic matter from continental shelves exposed by glacio-eustatic sea-level fall, which, in turn, promoted MPP again and resulted in Peak II. Thus, the TICE records complex climatecarbon cycle feedbacks that may have led to large-scale organic carbon burial and driven stepwise cooling, marking the onset of a sustained late Paleozoic icehouse climate.

DOI: 10.1130/G52447.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52447.1/649416/Zinc-isotope-perspective-on-global-carbon-cycling