Earth’s history has been marked by large volcanic eruptions, some of which caused climatic and biological disturbances that led to some of the most devastating extinction events in Earth’s history, and scientists are now shedding light on the timing and possible cause of these events, which occurred millions of years ago.
According to the “RT” website, a new study conducted by Trinity College Dublin revealed that the slowing of the movement of the continental plates was the critical event that enabled magma to rise to the Earth’s surface and cause devastating effects.
The surprising discovery is based on chemical data from ancient mudstone deposits that scientists obtained from a mile-deep well in Wales.
Lead author of the study, Dr Misha Ruhl, from Trinity College Dublin, said: “Scientists have long believed that the beginning of the rise of molten volcanic rock, or magma, from deep within the Earth’s interior, such as mantle plumes, was the instigator of such volcanic activity.” The new study shows that the natural rate of continental plate movement of several centimeters per year actually prevents magma from penetrating the continental crust of the Earth.
It appears that only when the velocity of continental plate movement slows to near zero magma from the mantle plumes can effectively make its way to the surface, causing major eruptions in the igneous provinces and associated climate disturbances and mass extinctions.
The largest volcanoes in the world are located in areas called Large Volcanic Regions (LIPs), which include the Siberian Traps (constituting a large region of volcanic rock, known as a Large Igneous Region in Siberia) in Russia, which extends over 500,000 square miles. for about a million years of epic volcanic activity.
The largest volcanic eruptions caused significant increases in carbon emissions to the atmosphere, which warmed the Earth’s climate, led to unprecedented changes in ecosystems, and to mass extinctions on land and in the oceans.
The international team of scientists participating in this study was able to link two major events that occurred during the Tursi period (the fourth stage of the Early Jurassic period), about 183 million years ago.
This time period was marked by some of the most extreme climatic and environmental changes ever, and coincided directly with significant volcanic activity and associated greenhouse gas emissions in the Southern Hemisphere.
Computer reconstruction models showed that the slowing of the movement of the continental plates was the basic geologic process that seemed to control the timing and onset of this and other major volcanic events.
Crucially, further assessment shows that the decrease in the movement of the continental plates is likely to have governed the onset and duration of many major volcanic events throughout Earth’s history, making them an essential process in controlling the evolution of climate and life on Earth’s surface throughout the history of this planet, according to Dr. Ruhl.
During the past 600 million years, there have been five major mass extinctions. While some have been well studied, others remain more enigmatic.
The first three extinctions occurred towards the end of the Ordovician period (about 445 million years ago), the end of the Devonian period (385 to 359 million years ago), and at the end of the Permian period (about 252 million years ago).
The most devastating of these events was the end of the Permian period, which wiped out about 96% of all marine species and about 70% of all known species on Earth.
Massive volcanic eruptions have occurred on an unprecedented scale, with other effects including the runaway greenhouse effect caused by the release of methane from craters on the sea floor. Recovery took about 10 million years.
The extinction at the end of the Triassic period, about 201 million years ago, mostly affected life in the oceans, with the extinction of a third of marine species. Some groups of reptiles on Earth have also become extinct.
The last mass extinction occurred 66 million years ago, when a city-sized asteroid hit the Gulf of Mexico and killed the dinosaurs.
The study helps to separate the different processes that control the changing global carbon cycle and turning points in the Earth’s climate system.
And it could have implications today, as the sixth mass extinction is already believed to be underway due to man-made global warming.