A new study led by Dr. LI Menghan at University of Science and Technology of China presents new evidence that nickel rich atmosphere may have played an important role in driving global environmental catastrophe which wiped out almost all life in the oceans.  

The end-Permian mass extinction of about 252 million years ago was the most severe biotic crisis in Earth’s history, killing more than 90% of marine animals such as corals, fusulinids, and ammonite as well as 75% of terrestrial species. Scientists believed that the eruption of the Siberian Traps large igneous province may have been the primary trigger for the environmental deterioration. However, the killing mechanisms depending critically on chemical compositions of the volatiles emitted by the Siberian Traps magmatism have remained mysterious.

Marine animals like corals (left) and fusulinids (middle) were killed suddenly during the end-Permian extinction. After the extinction, rocks contain few animal fossils (right) (Image by SHEN Yanan)

The study, published April 1 in the journal Nature Communications, reports Ni isotopic compositions of black shales from the well-preserved Buchanan Lake section in the Sverdrup Basin, Canadian High Arctic and the results reshape our understanding of global climate changes that caused the end-Permian extinction.

The Sverdrup Basin in Canadian High Arctic, ~20,000 km downwind of the Siberian Traps is an ideal place to study how atmospheric chemistry changes triggered by the Siberian Traps outgassing may have impacted chemical evolution of the oceans. Indeed, the Ni content and isotopic data from the Sverdrup Basin allow the researchers to provide a causal link between global environmental changes and the end-Permian extinction.

“Finding evidence of atmospheric chemistry changes preserved in the sedimentary rocks of 252 million years old is challenging,” LI said. “The lightest Ni isotopic compositions we documented provide strong evidence for massive deposition of Ni-rich atmospheric aerosols originated from the Siberian Traps outgassing.”

“Nickel is a bio-essential trace metal, like phosphate in the modern ocean. Fallout of the Ni-rich aerosols into the Sverdrup Basin would have increased marine productivity. Recycling of organic matter would have consumed lots of oxygen in seawater, causing ocean anoxia. Obviously, nearly all animals would have died without dissolved oxygen in seawater,” LI said. “In addition, the sharp decrease of Ni content near the extinction level likely marks the bloom of methanogens that produce methane gas. Collectively, our data illustrate a coherent picture showing how global climate changes catalyzed by Ni-rich aerosols may have caused the most devastating biotic crisis in Earth’s history.”

The research was supported by the National Natural Science Foundation of China. Co-authors on the study are Stephen Grasby from Canada Geological Survey, Shuijiong Wang from China University of Geoscience in Beijing, Laura Wasylenki from Northern Arizona University, Mingzhao Sun from ETH Zurich, Benoit Beauchamp from University of Calgary.

(Written by LU Hongyu, edited by LU Hongyu, USTC News Center)