A groundbreaking study sheds light on the breakup of southern Pangaea, revealing that a mantle plume played a crucial role in this geological event 135 million years ago. New research suggests that a massive thermal anomaly below the Earth’s surface triggered a gradual rift between South America and Africa. This wrenching tectonic event ignited one of the planet’s largest volcanisms.
The mantle plume, a rising column of superheated rock from Earth’s mantle, is believed to have been instrumental in generating the Iceland hotspot. This geologic hotspot has led to years of intermittent volcanic eruptions that are still a dominating feature of Iceland’s landscape today. Scientists think that this mantle plume connection is what makes the Iceland hotspot so unique. This fascinating connection implies that the same geological forces were at work during the breakup of southern Pangaea.
The new study shows that the majority of the major eruptions associated with the breakup occurred 135-131 million years ago. This intense period of activity occurred only about 134.5 million years ago. During this particularly explosive period, upwards of over 3.8 million cubic miles (16 million cubic kilometers) of magma exploded out. This tremendous flow changed the landscape almost overnight. The volcanic rock layers that are the legacy of these eruptions are particularly thick across the Northern Region. Indeed, some depressions in Namibia and Angola exhibit strata that extend as deep as 0.6 miles (1 kilometer).
This evidence points to a large, active thermal anomaly underneath what used to be southern Pangaea. This lends credence to the view that a mantle plume triggered the rifting that separated South America and Africa. This separation process was a slow one, taking nearly 55 million years to reach completion. Still, that divergence is happening even faster today—the Mid-Atlantic Ridge actively pulls apart about eight centimeters per year. It does it at the rate of 0.8 to 2 inches (2 to 5 centimeters) per year.
Mohamed Mansour Abdelmalak, a research fellow on the study, said these findings are highly relevant. He noted, “We don’t have many samples, so we don’t know exactly if this volcanism is related to the mantle plume.” This declaration highlights the still lingering battles that scientists go through in connecting ancient volcanism right to the most gentle geological hug.
The eruptions that shaped this period did more than just build mountains. Their effects were felt in all corners of the Earth. According to Abdelmalak, “We get some extinctions and some perturbations on the climate.” It was volcanic activity, which would dramatically reshape continents. It had devastating effects on biodiversity and climate change during that time period.
