Interesting seminar today from Prof. Richard O’Connell of Harvard Geophysics. Prof. O’Connell discussed the interplay between the thermal evolution of the Earth’s interior and plate tectonics.
Flow structure of the convection cell in a model of the Earth’s interior. Figure 3 from Crowley & O’Connell (2012) — http://adsabs.harvard.edu/abs/2012GeoJI.188…61C.
New models from Prof. O’Connell and his student John Crowley suggest that the Earth may have undergone different stages of tectonic evolution, with the tectonic plates moving quickly at some times in the Earth’s history but much more slowly at others.
The evolution between different geophysical modes may help explain a longstanding puzzle in Earth science: the amount of heat coming out of the Earth is much greater than expected and has been thought to require much more heating from radioactive isotopes than geochemical analyses allow.
If, instead, O’Connell and Crowley are right, then this large heat flow is really just a symptom of Earth’s geophysical fickleness: sometimes lots of heat comes out, other times less.