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Colossal volcanic eruptions like the kind that may have obliterated the dinosaurs more than 65 million years ago are caused by mantle plumes that rise from shifting underground mountains deep within the Earth's mantle, new research led by University of Wollongong (UOW) geophysicists and statistical scientists has revealed.

Published in Communications Earth & Environment, the strengthens scientists' understanding of Earth's evolution over hundreds of millions of years and provides new ways to locate minerals created by volcanic eruptions that are essential to the transition to a low-carbon economy.

The research team includes Ph.D. candidate Annalise Cucchiaro and Associate Professor Nicolas Flament from UOW's Environmental Futures research group, and Distinguished Professor Noel Cressie from the School of Mathematics and Applied Statistics.

"Researching the relationships between volcanic eruptions at the surface with such large-scale dynamic processes occurring 2,500 km below our feet puts into perspective how interconnected our planet really is," Cucchiaro said. "This work highlights the importance of mantle plumes in acting as 'magma highways' to the surface, creating these giant eruptions. It also shows that these plumes move along with their source, the BLOBS."

Mantle plumes are giant, slow-moving columns of hot rock that rise from deep inside the Earth, usually originating from two massive BLOBS (Big LOwer-mantle Basal Structures) about 2,500 kilometers down. One is under Africa and the other under the Pacific Ocean. Scientists have long debated whether BLOBS are fixed in place or slowly moving over millions of years.

The study has revealed that giant volcanic eruptions are connected to moving BLOBS. Reconstructing mantle convection from 1 billion years ago, the authors discovered that eruptions usually occur directly above or close to BLOBS, with the mantle plume gently tilting as it rises. Computer models show that volcanic hotspots like Hawaii tend to sit above areas where BLOBS have been located as they slowly move over millions of years.

Understanding whether these BLOBS are mobile helps scientists piece together the history of volcanic activity and predict where eruptions might happen in the future. This knowledge also allows researchers to reconstruct Earth's geological past, including how minerals such as diamonds are brought closer to the surface during powerful volcanic eruptions, like those that create kimberlite deposits.

"Giant volcanic eruptions have dramatic impacts upon life on Earth. They can wipe out life, like the dinosaurs, but also form rock formations that contain important minerals," Associate Professor Flament said. "This research cracks open one of the questions that has long plagued scientists—are the BLOBS stationary or mobile and how do they relate to giant volcanic explosions—so it is a thrill to finally be able to unravel these mysteries."

Giant volcanic eruptions also give rise to the discovery of new minerals buried deep below the Earth's surface, which, Associate Professor Flament said, are essential to the transition to a low-carbon economy. The next step for the research term is to explore the chemical nature of blobs and associated plume conduits.