(ORDO NEWS) — In the middle of the Permian period, large-scale volcanic eruptions began in the south of present-day China. They caused global warming and one of the “small” extinctions, the Keptenian.
However, the new work of geologists has shown that catastrophic events developed in two stages with a break of only three million years.
The middle stage of the Permian period – the Guadalupe era – began about 272 million years ago.
At that time, long before the dinosaurs, land was dominated by therapsids, ancient distant relatives and ancestors of mammals, including large predatory titanophoneus, which reached several meters in length.
They were put to an end by the Keptene mass extinction , which occurred about 260 million years ago.
It is not included among the five most terrible of such events, although some evidence indicates that the extent of the Keptenian extinction is greatly underestimated.
New work by scientists from the University of Cincinnati and their Chinese colleagues has shown that the end of the Guadalupe era was marked by not one, but two extinctions, separated by a very short, by geological standards, three million years.
Elevated mercury content in ancient rocks points to volcanic eruptions as the main culprits of the Keptenian extinction.
It is believed that traces of these catastrophic processes have survived in the form of the Emeishan traps , a vast igneous province in southwestern China.
Then they could fill the atmosphere with soot and dust, which blocked the sunlight and caused first a sharp cooling, and then, thanks to the greenhouse effect, a longer global warming.
Large amounts of carbon dioxide entering the water increased its acidity. The heated upper layers of the oceans dissolved oxygen worse, causing mass death of marine animals.
The content of this gas in water affects the rate of deposition of uranium isotopes, and it was their content in sediments at the bottom of the current South China Sea that Huyue Song and his colleagues investigated.
They found that the fall in oxygen at the end of the Middle Permian occurred twice: 262 million years ago and then 259 million years ago.
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