美国佛罗里达州立大学Stewart, E. M.团队报道了元古代地球强化的变质二氧化碳的释放。2024年9月23日出版的《美国科学院院刊》发表了这项成果。

据悉，岩石变质作用在地质时间尺度(>1My)上释放出大量的二氧化碳，潜在地驱动着长期的全球气候趋势。碳酸盐沉积物的性质和地壳热状态，对变质CO₂的释放效率起着重要的控制作用。因此，变质CO₂的脱气很可能在整个时间内都不是恒定的。

元古代地球的特点是含有大量白云石的混合碳酸盐-硅酸盐岩和较热的地壳结构，热液状态高，这两种状态都可能促进变质脱碳。热力学相平衡模型预测，中元古代的变质碳通量可能是现代地球的1.7倍。

研究人员使用分析和数值方法（碳循环模型preCONSCIOUS），来估计其将对元古代碳循环和全球大气成分产生的影响。与现代的脱气速率相比，这种增强的变质CO₂的释放可以使pCO₂增加4倍或更多，从而在地球早期生命扩张期间，造成更强的温室效应和全球气温升高。

附：英文原文

Title: Enhanced metamorphic CO₂ release on the Proterozoic Earth

Author: Stewart, E. M., Penman, Donald E.

Issue&Volume: 2024-9-23

Abstract: Rock metamorphism releases substantial CO₂ over geologic timescales (>1 My), potentially driving long-term planetary climate trends. The nature of carbonate sediments and crustal thermal regimes exert a strong control on the efficiency of metamorphic CO₂ release; thus, it is likely that metamorphic CO₂ degassing has not been constant throughout time. The Proterozoic Earth was characterized by a high proportion of dolomite-bearing mixed carbonate-silicate rocks and hotter crustal regimes, both of which would be expected to enhance metamorphic decarbonation. Thermodynamic phase equilibria modeling predicts that the metamorphic carbon flux was likely ~1.7 times greater in the Mesoproterozoic Era compared to the modern Earth. Analytical and numerical approaches (the carbon cycle model PreCOSCIOUS) are used to estimate the impact this would have on Proterozoic carbon cycling and global atmospheric compositions. This enhanced metamorphic CO₂ release alone could increase pCO₂ by a factor of four or more when compared to modern degassing rates, contributing to a stronger greenhouse effect and warmer global temperatures during the expansion of life on the early Earth.

DOI: 10.1073/pnas.2401961121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2401961121