HomePhotographyThe Permian-Triassic mass extinction, the largest ever documented

The Permian-Triassic mass extinction, the largest ever documented

Permian extinction

252 million years ago life on our planet was on the verge of disappearing. The magnitude of this event was such that it was given the name “The Great Dying” or “The Great Extinction”: outside 90% marine species and approximately 75% terrestrial they disappeared.
Let’s reconstruct the events at the end of Permian they launched the most devastating mass extinction that ever occurred on Earth.

Permian-Triassic extinction

Mass extinction

Let’s start by reminding ourselves that extinction is part and parcel of natural development. A species or other taxonomic group may become extinct if the environment becomes hostile to their survival or because of competition with other life forms. It is estimated that approximately 98% of all kinds of animal and plant organisms that ever lived on our planet are extinct today.

pictureIntensity of marine extinction over time. The blue graph shows the apparent percentage (not the absolute number) of extinct genera. Credits: Wikimedia Commons.

The natural rate of extinction is estimated to be approx 0.1-1 species per million each year. Instead, we are talking about a mass extinction, when a large number of species in general more than 70% of the global total, disappear in a short geologic time interval, usually less than 4 million years. It is about exceptional events triggered by drastic environmental changes and often associated with natural disasters such as astronomical impacts or large-scale volcanic activity.

You are surely aware of the events that approximately 66 million years ago, at the end of the Cretaceous period, caused the disappearance of more than 78% of the species existing on the planet, including the dinosaurs. However, the most devastating mass extinction documented to date occurred ca 252 million years ago, marking the transition from Permian to Triassic.

Causes of the Permian-Triassic extinction

Over the past 60 years, several hypotheses have been formulated to explain the Late Permian extinction. Some scientists attribute extinction to the origin of the supercontinent Pangea would alter the circulation of ocean currents and reduce the extent of shallow marine habitats, causing a decline in biodiversity with consequent impacts on the oxygen cycle. Other geologists have proposed extraterrestrial causes, such as the design hypothesis of cosmic rays and just as it was in the Cretaceous, meteorite impact.

picture
Paleogeographic reconstruction of the supercontinent Pangea during the Late Permian.

Today, however, overwhelming evidence has led most of the scientific community to acknowledge environmental-induced changes in Siberian Traps Great Magmatic Province as the main cause of extinction. For a better understanding of the Great Magmatic Province, or large igneous provinces are areas where huge volumes of igneous melt, usually of basaltic composition, penetrate the uppermost levels of the earth’s crust and/or are erupted in extremely short geological periods, usually less than 5 million years. These events are often associated with the rise of magma plumes from the mantle. The products of the activity of large magmatic provinces can cover an area exceeding one million reaching volumes even exceeding one million km3.

Large igneous provinces are relatively rare in the geological history of our planet, but they seem to have often played a key role in climate change and mass extinction processes. The figure below shows the location of some known large igneous provinces. The Great Siberian Traps Igneous Province, located in northern Siberia, Russia, is one of the largest magmatic provinces ever discovered. Volcanic activity associated with this province, which occurred between 252.24 and 250.2 million years ago, is estimated to have covered an area of more than 5 million km2. For comparison, India covers an area of ​​almost 3.3 million km2.

But what is the connection between this event confined to Siberia and the extinction that occurred on a global scale?

Siberian Traps Great Magmatic Province

The Putorana Plateau is composed of Siberian paste basalts.  Credits: Wikimedia commons.
The Putorana Plateau consists of Siberian paste basalts. Credits: Wikimedia Commons.

The beginning of the extinction phase coincides with the formation of ampules of magmatic sills in sedimentary rocks Tunguska basin. Sills are tabular intersections that form in the earth’s crust more superficial during magma ascent. Accurate radiometric dating indicates this 251.907 million years ago, sill formation became the dominant process in the magmatism of the Great Magmatic Province of the Siberian Traps.

According to a model proposed in 2017 by a team of researchers from the USGS (United States Geological Survey) and MIT (Massachusetts Institute of Technology), sills would form inside rocks containing volatile components and organics such as evaporites, carbonate rocks, and black shale. Heating of these rocks caused by contact with magma would cause release into the atmosphere huge amounts of greenhouse gases leading to a series of chain reactions and environmental disturbances that would contribute to extinction.

Evolution in a continental environment

An increase in concentrations of carbon dioxide, sulfur dioxide, and methane in the atmosphere would contribute to global warming AND acidification. These events would be among the main causes devastation of terrestrial ecosystems at the end of the Permian. The reduction of vegetation would then contribute to the acceleration of surface erosion processes.

They have been observed in many places changes in river morphology, with a transition to high-energy systems such as braided currents capable of transporting large volumes of sediment into ocean basins. Several factors may have triggered this change, including the disappearance of riparian vegetation, increased intensity of low- and mid-latitude monsoon rainfall, local tectonic activity, or a combination of these factors. In addition, fires have played a significant role in the destruction of terrestrial ecosystems with the local development of hyper-dry states.

pictureSchematic illustration of the possible evolution of the Earth’s environment across the Permian-Triassic boundary. EPE = end–Permian extinction event. Credits: Nature Communications / Ways et al., 2021.

Extinction in the oceans

The exact process that led to the extinction of the oceans is not entirely clear, but it is believed to have been a combination of factors. Several models suggest that ocean temperatures will increase by approximately 6-10 °C, as a result of climatic changes induced by the Great Magmatic Province of the Siberian Trap. Next, the passage of CO2 in solution, through chemical-physical and biological processes, would lead to rapid ocean acidification. Both processes would help create a marine environment hostile to life and the organisms that proliferated there. In addition, several lines of evidence suggest the onset of conditions anoxia or lack of dissolved oxygen in the water column. Finally, some researchers hypothesize that the large volume of sediment transported by waterways into ocean basins may have contributed to the destabilization of shallow marine habitats and theerential extinction of benthic communities.

Consequences of extinction

Marine invertebrates suffered the most significant losses, including the disappearances of trilobites and the god’s eurypterids (also known as sea scorpions) as well as a drop of over 96% in crinoids and ammonites. further more than 93% of foraminiferal species disappeared after the events that marked the end of the Permian.

Rendering of the Permian extinction

On the continent, more than two-thirds of the species of amphibians, sauropsis (similar to reptiles), and therapists (ancestors of mammals) disappeared. Extinction has also hit the human world hard insects, which instead recorded considerable diffusion and speciation during the Permian. Vegetation was not immune to this event, with a drastic reduction in biodiversity and a change in the dominant fauna. However, the extent of the plant extinction is not fully understood, and recent studies suggest that it may have been less devastating than previously thought.

Remains of Aulacephalodon peavoti specimen, belonging to the order Therapsida and extinct in the Upper Permian.  Credits: Wikimedia commons.
The remains of the specimen Aulacephalodon peavoti, belonging to the order Therapsida and extinct in the Late Permian. Credits: Wikimedia Commons.

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  • Geekay Dutta

    Welcome to my world! I'm Goutam Kumar Dutta, the brains behind this platform. As an author and the proud owner of this site, I'm on a mission to bring you the latest and most intriguing sports news from various genres. But it's not just about sports - entertainment in all its forms also captivates my interest. Whether it's analyzing the latest match or delving into the world of entertainment, I strive to provide comprehensive coverage and valuable insights.

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