Transfer of heat through the Earth is accommodated by the slow creeping of solid rock. The mantle can move thousands of kilometers in the millions of years it takes for supercontinents to break apart and species to evolve. Forming a key component of this transfer, mantle plumes are upwelling currents that carry heat from the deep Earth to the surface. They are responsible for forming ocean island chains, uplifting continental interiors, and episodic outpourings of large volumes of volcanic rock that have been linked to mass extinction events.
For 30 years, geoscientists have been using the shape of uplifted topography above individual plumes to estimate their relative sizes and heat content. These studies find that only ~5% of heat escaping through the Earth’s surface is transported through the mantle by upwelling plumes, which suggests that they play only a minor role in the thermal budget.
However, evidence from convection simulations, seismology, the geochemistry of volcanic rocks, and estimates of heat flow into the base of the mantle, all suggest that plumes are a significant component of mantle dynamics. In a paper (PDF) just out in Earth and Planetary Science Letters, we therefore revisit this issue and suggest that pre-existing values of plume flux are likely to be underestimates. We collate a new global inventory of plume magnitudes, and discuss how improved measurements might be made in future studies.
