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[交流] A climate threshold for ocean deoxygenation during the Early Cretaceous

A climate threshold for ocean deoxygenation during the Early Cretaceous

白垩纪早期海洋脱氧的气候阈值

▲ 作者:Kohen W. Bauer, N. Ryan McKenzie et al.

▲链接:

https://www.nature.com/articles/s41586-024-07876-1

▲摘要:

在此,我们的研究显示,在白垩纪大洋缺氧事件(OAE1a)期间海洋快速脱氧与火山二氧化碳排放和相关气候阈值的跨越有关。此后,硅酸盐风化反馈和气候恢复的缓慢步伐将再氧化的延迟事件大于1百万年。在OAE1a结束时,重新越过这个阈值并使得海洋再氧化。

然而,在OAE1a之后,地球系统保持足够的温暖,以至于轨道驱动的气候动力学导致海洋在大约10亿年的时间尺度上继续循环脱氧,并持续了1百万年。因此,我们的结果暗示了火山作用、风化作用和海洋氧含量之间的紧密耦合,这种耦合以气候阈值为特征。

▲ Abstract:

Here we show that rapid ocean deoxygenation during OAE1a is linked to volcanic CO2emissions and the crossing of an associated climate threshold, after which the sluggish pace of the silicate-weathering feedback and climate recovery delayed reoxygenation for >1 Myr. At the end of OAE1a, recrossing this threshold allowed for ocean reoxygenation. Following OAE1a, however, the Earth system remained sufficiently warm such that orbitally forced climate dynamics led to continued cyclic ocean deoxygenation on approximately 100-kyr timescales for another 1 Myr. Our results thus imply a tight coupling between volcanism, weathering and ocean oxygen content that is characterized by a climate threshold.
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