New research has discovered that a continental breakup that took place 135 million years ago brought major destruction. The splitting of South America and Africa saw an outburst of 16 million cubic kilometres of magma, which can still be found as volcanic rocks on both continents and the Atlantic Ocean’s sea floor. Volcanic rocks up to one kilometre thick can be spotted in countries including Namibia and Angola
The new study, made up of various sources of previously collected data from South America, Africa and the ocean floor, uncovers that the main magma eruptions took place between 135 million and 131 million years ago, with a peak around 134.5 million years ago. The better understanding of the time the eruption happened could offer researchers a more clear idea of what triggered the break up as well as its impacts on the climate, Live Science reports.
Additionally, the research finds evidence of a “thermal anomaly” beneath what was then southern Pangaea, a supercontinent that started to break up 200 million years ago into the continents we have today. The separation was slow, with South America and Africa splitting 135 million years ago, yet, the division between North America was only complete up until 55 million years ago.
The break up of southern Pangaea happened partly because of what is known as a mantle plume, according to research suggestion. A mantle plume is a large column of hot, buoyant material which rises from the mantle, the Earth’s middle layer. The plumes melt and narrow down the continental crust from below.
Mohamed Mansour Abdelmalak, a geologist and geophysicist at the University of Oslo in Norway, and the study lead author told Live Science that the new research hints that the thermal anomaly that contributed to the separation of South America and Africa, was as a result of the mantle plume. However, the hypothesis remains a controversial one.
He said: “We don’t have many samples, so we don’t know exactly if this volcanism is related to the mantle plume.” Samples from the rock which lies under the deep ocean off the coast of Argentina and Uruguay, where very little deep-sea drilling has taken place, are needed in particular.
Mohamed Mansour Abdelmalak also shared that additional deep rock samples from Africa and the deep ocean could aid the researchers in understanding how much magma erupted during the split between the Africa and South America, as well as the effect it had on the climate.
What happens in most cases of large eruptions is the climate warms as a result of the volcanoes spewing huge amounts of greenhouse gases. However, there was a period of cooling 134 million years ago, potentially because the magma that erupted, either broke down, or weathered quickly.
When weathering takes place, rocks break down and chemically react with the air, drawing carbon dioxide out of the atmopshere.
