A new study of the East Pacific Rise, a mid-ocean ridge, suggests plate dynamics are driven significantly by the buoyancy force provided by heat rising from Earth's core. Photo by University of Chicago/Wikimedia Commons
Jan. 18 (UPI) -- New mantle convection models show heat from Earth's core is a driving factor of plate tectonics. Until now, scientists believed cooling was the primary factor.
Current tectonics models also operate on the assumption that mid-ocean ridges are passive boundaries. Analysis by researchers at the University of Chicago has shown that assumption to be false.
A closer look at the East Pacific Rise, a major mid-ocean ridge, revealed a dynamic system, strongly influenced by heat transfer from the mantle.
"We see strong support for significant deep mantle contributions of heat-to-plate dynamics in the Pacific hemisphere," David B. Rowley, professor of geophysical sciences at Chicago, said in a news release. "Heat from the base of the mantle contributes significantly to the strength of the flow of heat in the mantle and to the resultant plate tectonics."
If subduction -- the sinking of plate material caused by cooling at the surface -- was the sole or dominant factor in plate tectonics, the East Pacific Rise should have shifted more dramatically over the last 50 to 80 million years. The ridge has spread out asymmetrically but has not moved east or west.
The buoyancy force provided by mantle heat explains the ridge's static state.
"The East Pacific Rise is stable because the flow arising from the deep mantle has captured it," Rowley said. "This stability is directly linked to and controlled by mantle upwelling," the rising heat from Earth's core to the surface.
Using their new model, scientists calculated that as much as 20 terawatts of heat flows from the core to the mantle, accounting for 50 percent of plate dynamics.
Because most plate tectonic and mantle convection models have discounted the buoyancy of heat rising from the core, scientists will be forced to reconsider previous findings.
"Based on our models of mantle convection, the mantle may be removing as much as half of Earth's total convective heat budget from the core," Rowley said. "The implication of our work is that textbooks will need to be rewritten."
Rowley and his colleagues published their new findings in the journal Science Advances.