近日，美国罗格斯大学Black, Benjamin A.及其团队成员，研究了洪水玄武岩事件后的隐蔽性脱气和长期温室气候。这一研究成果于2024年10月30日发表在国际顶尖学术期刊《自然—地球科学》上。
据介绍，大火成岩省向地球表面喷发高活性的、主要为玄武质的熔岩，将会促使风化通量增加，引起长期的二氧化碳排放量减少和火山活动停止后的冷却。然而，纵观地球的地质历史，多个显生宙大火成岩省的后果是持续了数百万年的长期气候变暖和生物复苏迟缓，超过了火山活动作用的最大规模阶段。
研究团队对地幔熔融进行了地球动力学模拟，对岩浆运移进行了热力学模拟，结果表明，尽管有持续的熔融体产生和二氧化碳供应，但地壳中的流变反馈可以抑制喷发速率。研究人员表示，在大火成岩省期间，地幔来源的二氧化碳向大气的通量可以与地表火山活动的速率分离，地表火山活动代表了驱动长期气候的重要通量。
研究利用时间校准的古生物数据进行跨区间气候-生物地球化学模拟，进一步显示这种非喷发的隐蔽性二氧化碳，如何有助于协调大火成岩省的生命周期，与二叠纪-三叠纪、中新世中期和地球气候历史上其他关键时刻的气候破坏和恢复。研究结果强调了，侵入岩浆的除气在调节行星表面环境中的关键作用。
附：英文原文
Title: Cryptic degassing and protracted greenhouse climates after flood basalt events
Author: Black, Benjamin A., Karlstrom, Leif, Mills, Benjamin J. W., Mather, Tamsin A., Rudolph, Maxwell L., Longman, Jack, Merdith, Andrew
Issue&Volume: 2024-10-30
Abstract: Large igneous provinces erupt highly reactive, predominantly basaltic lavas onto Earth’s surface, which should boost the weathering flux leading to long-term CO2 drawdown and cooling following cessation of volcanism. However, throughout Earth’s geological history, the aftermaths of multiple Phanerozoic large igneous provinces are marked by unexpectedly protracted climatic warming and delayed biotic recovery lasting millions of years beyond the most voluminous phases of extrusive volcanism. Here we conduct geodynamic modelling of mantle melting and thermomechanical modelling of magma transport to show that rheologic feedbacks in the crust can throttle eruption rates despite continued melt generation and CO2 supply. Our results demonstrate how the mantle-derived flux of CO2 to the atmosphere during large igneous provinces can decouple from rates of surface volcanism, representing an important flux driving long-term climate. Climate–biogeochemical modelling spanning intervals with temporally calibrated palaeoclimate data further shows how accounting for this non-eruptive cryptic CO2 can help reconcile the life cycle of large igneous provinces with climate disruption and recovery during the Permian–Triassic, Mid-Miocene and other critical moments in Earth’s climate history. These findings underscore the key role that outgassing from intrusive magmas plays in modulating our planet’s surface environment.
DOI: 10.1038/s41561-024-01574-3
Source: https://www.nature.com/articles/s41561-024-01574-3
来源：科学网 小柯机器人