Yamaguchi University

The University of Tokyo Graduate School of Science

Summary of Presentation

The Late Permian mass extinction, the third of the five major mass extinctions, occurred about 250 million years ago and was the largest extinction in the history of life on Earth, resulting in the extinction of more than 90% of species. The cause of the Late Permian mass extinction is thought to have been large-scale volcanic activity that occurred northeast of the supercontinent Pangaea, in what is now Siberia. However, although this volcanic activity lasted for more than 900,000 years, the Late Permian mass extinction occurred within a period of only about 60,000 years. This significant time gap between cause and effect is one of the mysteries of the Late Permian mass extinction. High-resolution analysis of the stratigraphic record has been sought to elucidate the cause of this temporal gap, but due to technical limitations, this has not yet been accomplished.

To solve this mystery, a research group led by Assistant Professor Ryosuke Saito of the Graduate School of Frontier Sciences, Yamaguchi University, has succeeded in analyzing the uppermost stratigraphic record of the Permian system at an ultra-high resolution (0.1 mm), 100 times higher than that of conventional methods, by using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). The results of the analysis showed that the stratigraphic record of the uppermost part of the Permian system was analyzed at an ultra-high resolution (0.1 mm), more than 100 times higher than previous studies. As a result, it became clear that a series of environmental degradations, i.e., terrestrial fires caused by volcanic activities, discharge of terrestrial soil into the ocean, and anoxia of the ocean, have repeatedly occurred over a time scale of several hundred years. This indicates that the degradation of the terrestrial and marine environments are closely related and yet occur on a short geologic time scale.

The results of this study were published electronically on April 14 at 10:00 a.m. (London time) prior to publication in the international journal Nature Communications.

Figure: Fire record of about 250 million years ago analyzed in this study. Black and red lines indicate results from FT-ICR-MS and conventional analytical methods, respectively. Fire and soil discharge into the ocean occurred repeatedly on a scale of several hundred years during the mass extinction at the end of the Permian, and the ocean became anoxic during the same period.

The research results were supported by Assistant Professor Ryosuke Saito (formerly Project Assistant Professor, Department of Earth and Planetary Science) of Yamaguchi University, Associate Professor Satoshi Takahashi (formerly Assistant Professor, Department of Earth and Planetary Science) of Nagoya University, and Associate Professor Masayuki Ikeda of the Department of Earth and Planetary Science.

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