New research led by Professor Shen Yanan at the University of Science and Technology of China (USTC) reveals that the melting of the Sturtian "Snowball Earth" induced large-scale volcanic activities and the gradual oxidation of interglacial oceans created favorable environmental conditions for the evolution of complex life. The study was recently published inScience Advances.
The Stutian Snowball Earth glaciation began 717 million years ago and lasted for about 56 million years, and it represents the most extreme climate change in Earth’s history. Understanding the Earth system evolution during the ice melt is closely relevant to the modern climate change as the Earth warms today.
“We used two independent isotopic proxies of mercury and sulfur to constrain the environmental changes at the end of Sturtian Snowball glaciation. Our data show an evolutionary picture of ice melting, volcanism and climate warming, ocean chemistry change, and life evolution,” said the study's lead author, Dr. Menghan Li who conducted the research at USTC.
Scientists focused their study on the Datangpo Formation in South China which not only hosts large and even super-large sedimentary manganese deposits in China but also provides a nearly complete record of the climate and environmental changes between two "Snowball Earth" events. The findings shed new light on the co-evolution of climate change and early complex life.
Scientists found that the chemical composition of seawater was dominated by hydrothermal components during the initial thawing stage of the "Snowball Earth". This finding is consistent with the “Snowball Earth” theory, showing that the ocean chemistry of the Snowball deepwater was inherited when the ice was melting. In addition, the Hg isotopic data provide strong evidence for large-scale volcanic activity during the rapid melting of the “Snowball Earth” glaciation.
"Enhanced terrestrial magmatism associated with the unloading of ice sheets and decompression melting is expected in the aftermath of Snowball Earth glaciations. It's like lifting a huge boulder from the ground, and the suppressed magma suddenly erupted," said Li Menghan.
The volcanic response to ice melting has caused climate warming and ocean anoxia. The finding shows a clear interaction between the Earth’s surface environmental changes and its deep activities.
“Our study shows that a dramatic change in any part of the interconnected Earth system could trigger catastrophic consequences,” said Yanan Shen.
(Picture drawn by Yang Dinghua)
The ocean became to be more habitable when the volcanic activities were gone, according to the study. The temporal variations in sulfur isotopes demonstrate a gradual increase in seawater sulfate concentration, indicating a progressive oxidation of the atmospheric and oceanic systems during that period. A gradual decrease in Earth’s surface temperatures and the oxygenation of the oceans may have facilitated the evolution of early complex life forms.
More information: Li, M., Xu, Y., Sun, L., Chen, J., Zhang, K., Li, D., Farquhar, J., Zhang, X., Sun, R., Macdonald, F.A., Grasby, S.E., Fu, Y., Shen, Y., 2023. Deglacial volcanism and reoxygenation in the aftermath of the Sturtian Snowball Earth. Science Advances 9, eadh9502. DOI: 10.1126/sciadv.adh9502
(Written by JIANG Zhimo,EditedbyMA Xuange, USTC News Center)
