The Earth’s sprawling ocean ridge system is a result of overturning material in its interior, where boiling temperatures can melt and eject rocks up through the crust, splitting the sea floor and reshaping the planet’s surface over hundreds of millions of years.
Geologists at MIT have now analyzed thousands of samples of erupted material along ocean ridges and traced back their chemical history to estimate the temperature of the Earth’s interior.
Their research shows that the temperature of the Earth’s underlying ocean ridges is fairly consistent, at around 1,350 degrees Celsius – about as hot as a gas range’s blue flame. There are, however, hotspots along the ridge that can reach 1,650 degrees Celsius.
The team’s results provide a temperature map of the Earth’s interior around the ocean ridges. With this map, scientists can better understand the melting processes that produce undersea volcanoes, and how these processes may drive the pace of plate tectonics over time.
“Convection and plate tectonics have been important processes in shaping Earth’s history,” says lead author Stephanie Brown Krein. “Knowing the temperature along this whole chain is fundamental to understanding the planet as a heat engine, and how Earth might be different from other planets and able to sustain life.”
Because there is no way to directly read the temperature tens to hundreds of kilometers below the surface, scientists have applied indirect means to infer the temperature of the upper mantle.
For their study, Krei and her colleagues developed a new algorithm, called ReversePetrogen, that is designed to trace the chemical history of a rock back in time, to identify its original composition of elements and determine the temperature at which the rock initially melted below the surface.
“You could effectively make a model of the temperatures of the entire interior of the Earth, based partly on the temperature at these ridges,” Krein says. “The question is, what is the data really telling us about the temperature variation in the mantle along the whole chain?”
https://phys.org/news/2021-07-geologists-earth-temperature-erupted-sea.html