Metamorphic decarbonation in the Neoproterozoic and its environmental implication
Metamorphic decarbonation in the Neoproterozoic and its environmental implication
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DOI：
10.1016/j.gr.2008.01.006
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发表时间：
2008-08
影响因子：
6.1
通讯作者：
S. Omori;M. Santosh
中科院分区：
文献类型：
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作者：
S. Omori;M. Santosh
变质脱碳反应和火山脱气导致主要温室气体二氧化碳从固体地球大量流入海洋-大气系统。本文通过对新元古代超高温变质作用的矿物学和地质学分析，对新元古代超高温变质过程中变质脱气所产生的二氧化碳进行了定量估算。我们的计算表明，通过喜马拉雅尺度的UHT变质作用，向大气中添加了额外的CO2通量，其程度为6×1016-3.0×1018mol/my，持续10分钟。在碳循环和CO2温室效应的背景下，计算了额外的CO2流入对全球平均温度的影响，结果表明，在高峰流入阶段，稳态温度将从15℃上升4℃，从4℃上升13℃。我们的结果对评估雪球地球的融化机制和持续时间具有重要意义。我们对超高温变质过程中最大脱气速率的估计表明，马里诺雪球地球的持续时间可能较短，从冰盖地球到海洋覆盖地球的恢复速度比之前的估计要快。
Metamorphic decarbonation reactions and volcanic degassing lead to significant influx of CO2, a major greenhouse gas, into the ocean-atmosphere system from the solid Earth. Here we present quantitative estimates on CO2derived through metamorphic degassing during ultrahigh-temperature (UHT) metamorphism in the Neoproterozoic through the mineralogical and geological analyses of the UHT decarbonation. Our computations show that an extra flux of CO2was added to the atmosphere through a Himalayan scale UHT metamorphism to the extent of 6 × 1016to 3.0 × 1018mol/my, for a duration of 10 my. A calculation of the impact of the extra CO2influx to the global mean temperature in the context of carbon cycle and greenhouse effect of CO2shows that at the peak influx stage, the steady state temperature would be raised by 4 °C from 15 °C and by 13 °C from 4 °C. Our results have important bearing in evaluating the mechanism of melting and the duration of the Snowball Earth. Our estimate of the maximum degassing rate during UHT metamorphism suggests that the duration of the Marinoan snowball Earth was probably shorter, and the recovery from an ice-covered Earth to ocean-covered Earth was faster than previous estimates.