Subterranean Trees of Magma →September 15, 2021 • #
From the world of geophysics, a massive-scale seismic research project has been happening surrounding the island of Réunion, a shield volcanic dome over an Indian Ocean hotspot. Researchers have been using a stream of data collected from a web of seismometers in the region to map out the superheated plumes of mantle material that bubble up from the core.
In 2012, a team of geophysicists and seismologists set out to map the plume, deploying a giant network of seismometers across the vast depths of the Indian Ocean seafloor. Nearly a decade later, the team has revealed that the mantle is stranger than expected. The team reported in June in Nature Geoscience that the plume isn’t a simple column. Instead, a titanic mantle plume “tree” rises from the fringes of the planet’s molten heart, with superheated branchlike structures appearing to grow diagonally out of it. As these branches approach the crust, they seem to sprout smaller, vertically rising branches — super hot plumes that underlie known volcanic hot spots at the surface.
The data has resulted in higher-resolution 3D modeling of these plumes than we’ve seen before, showing how fractal, tree-like structures happen even in geophysical processes embedded in the earth. These patterns are everywhere in nature, even in slow-moving rock. The article comes with some cool graphics showing what these structures look like, stretching from the core up to the surface forming continent-sized columns.
Geologic timescales are impossible to comprehend in their scale. So I love it when writers accelerate the events for effect:
Some scientists suspect that plumes from the African giant blob spent at least 120 million years tearing the ancient supercontinent of Gondwana into shards. As the plumes rose into its base, they heated it and weakened it; like moles making hills, they caused the land atop these plumes to dome upward, then slide downhill. Australia was unzipped from India and Antarctica, Madagascar from Africa, and the Seychelles microcontinent from India — an act of destruction that made the Indian Ocean.
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