Researchers Saikiran Tharimena, Catherine Rychert and Nicholas Harmon at the University of Southampton have published exciting results in the journal Science about the thickness of the continents and the defining mechanism of the tectonic plate.
The thickness of the continental portion of Earth’s cold and rigid plates is a source of debate. Previous attempts to measure the thickness of Earth’s tectonic plates have yielded vastly different results. Fragments of rock from deep below, brought up to the surface by volcanism, provide the best direct evidence of subsurface composition and thermal structure. Yet analyses of such rocks, called xenoliths, suggest that tectonic plates are about 175 km thick, whereas seismic tomography imaging indicates that the continents are up to 400 km thick. The researchers used a sophisticated technique to measure seismic reflections off of surfaces to probe the depths below tectonic plates using over 25 years of teleseismic data. Their data reveals that the thickness of the continents range from 130 – 190 km depth, which lines up well with the depth where diamonds are stable—an independent line of evidence for the depth of continents. These depths also correspond to where small amounts of melt reside, right under the continental plates.
You can access the full paper at the link below:
A unified continental thickness from seismology and diamonds suggests a melt-defined plate
A summary of the paper can be found at
Science: A seismic shift in continental tectonic plates
Cosmos Magazine: How thick is a continent? Seismic waves and diamonds hold clues
Phys.org: An improved thickness estimate for Earth’s continents