Enhanced magmatism played a dominant role in triggering the Miocene Climatic Optimum
Enhanced magmatism played a dominant role in triggering the Miocene Climatic Optimum
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DOI：
10.1038/s43247-023-00684-x
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发表时间：
2023-01
影响因子：
7.9
通讯作者：
K. Goto;M. Tejada;E. Tajika;Katsuhiko Suzuki
中科院分区：
文献类型：
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作者：
K. Goto;M. Tejada;E. Tajika;Katsuhiko Suzuki
中新世气候适宜期是新生代主要的气候变暖事件之一，并伴随着稳定碳同位素的正漂移。在这里，我们报告了来自太平洋沉积物的海水锇同位素数据，以确定同时代岩浆活动的二氧化碳排放是否可能是这一事件的触发因素。我们的数据显示，负锇同位素偏移从0.80至0.72之间约17和1580万年前，可以解释在此期间增强岩浆活动。简单的质量平衡计算表明，在此期间，从地幔进入海洋的非放射性锇输入增加了22 - 45%。使用锇同位素组成作为全球碳循环模型的约束条件，我们发现岩浆活动的增加能够使大气二氧化碳浓度升高65 × 140 ppmv，并导致海水稳定碳同位素的正偏移0.4 × 0.7‰，与地球化学观测结果一致。我们的结论是，这是可以想象的，加强岩浆活动发挥了主导作用，导致中新世气候最佳。
The Miocene Climatic Optimum represents one of the major warming events during the Cenozoic and was accompanied by a positive stable carbon isotope excursion. Here, we report seawater osmium isotope data from Pacific Ocean sediments to determine if carbon dioxide emissions from coeval magmatism could have been the trigger for this event. Our data reveal a negative osmium isotope excursion from 0.80 to 0.72 between about 17 and 15.8 million years ago that can be explained by enhanced magmatism during this period. Simple mass balance calculations suggest an increase of 22‒45% in non-radiogenic osmium input from the mantle into the ocean during this period. Using osmium isotopic composition as a constraint for global carbon cycle modelling, we find that such an increase in magmatism is capable of elevating atmospheric carbon dioxide concentrations by 65‒140 ppmv and of causing a positive excursion in seawater stable carbon isotopes of 0.4‒0.7‰, consistent with geochemical observations. We conclude that it is conceivable that the enhanced magmatism played a dominant role in causing the Miocene Climatic Optimum.