The Middle Eocene Climatic Optimum (MECO), a ∼500 kyr episode of global warming that initiated at ∼ 40.5 Ma, is postulated to be driven by a net increase in volcanic carbon input, but a direct source has not been identified. Here we show, based on new and previously published radiometric ages of volcanic rocks, that the interval spanning the MECO corresponds to a massive increase in continental arc volcanism in Iran and Azerbaijan. Ages of Eocene igneous rocks in all volcanic provinces of Iran cluster around 40 Ma, very close to the peak warming phase of the MECO. Based on the spatial extent and volume of the volcanic rocks as well as the carbonaceous lithology in which they are emplaced, we estimate the total amount of CO₂ that could have been released at this time corresponds to between 1052 and 12 565 Pg carbon. This is compatible with the estimated carbon release during the MECO. Although the uncertainty in both individual ages, and the spread in the compilation of ages, is larger than the duration of the MECO, a flare-up in Neotethys subduction zone volcanism represents a plausible excess carbon source responsible for MECO warming.

中文翻译：

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探索中始新世最佳气候与新特提斯大陆弧爆发之间的联系

中始新世气候适宜期（MECO），一个约500  KYR全球气候变暖，在开始的插曲〜  40.5 麻，假定由火山碳输入的净增加来驱动，而是直接来源尚未确定。在此，根据新的和先前发布的火山岩辐射年龄，我们证明，跨越MECO的间隔对应于伊朗和阿塞拜疆的大陆弧火山作用的大量增加。伊朗所有火山省的始新世火成岩年龄都集中在40 Ma左右 ，非常接近MECO的峰值升温阶段。根据火山岩的空间范围和体积以及其所处的碳质岩性，我们估算了火山岩的总量。此时可能释放的CO ₂对应于1052和12565  Pg之间的碳。这与MECO期间的估计碳排放量相符。尽管两个年龄段的不确定性以及年龄段的分布范围都大于MECO的持续时间，但新特提斯俯冲带火山爆发的爆发代表了造成MECO变暖的合理的过量碳源。