Presentation #1248 in the session “Open Engagement Session C”.
Earth’s surface topography counts very few points on land antipodal to other points on land. Moreover, this “antipodal anticorrelation” has been a feature of the globe at least since the break-up of Pangaea. We quantify this by calculating topographical power spectra, and present evidence that anticorrelation is preferred and maintained by the motions of plate tectonics. That is, mantle convection, as supported through our parallel analysis of plate velocities, appears to inhibit erasure of anticorrelation on the time scales of supercontinent break-up and re-formation. This hypothesis gains support from published work that links the plate structure and size distribution to the dynamics of mantle convection and its influence on the lithosphere, and shows preferences for a specific parity in surface harmonic structure. We corroborate this with our own fully-3D models of mantle convection.
Combining these spectral analyses with a simple model of erosion and volcanism, we are also able to estimate — if Venus also had active plate tectonics at some point in its history — how long it has been in its current stagnant lid state. Our analysis estimates this transition occurred roughly 600 million years ago. In the context of future exoplanetary characterization, if active plate tectonics are a potential requirement of planetary habitability, antipodal anticorrelation may constitute an important observable clue.