Ie: Can these very similar values all have a common origin--perhaps in the
mutual spin and tidal interactions of the Earth-Moon-Sun system? The usual
driver for mantle (and plate) motion is said to be due to the heat flow and
the local geochemistry of the Earth's interior, and of course the decay of
several radionuclides. Ie: Is this similarity between (1, 2) and (3)
merely a quirky coincidence? Or, over billions of years, have all three
processes achieved some mutual energetics 'partitioning' balance?

[[Mod. note -- It's a coincidence. -- jt]]

Earth core heating can be stated as an effect of Sun/Earth/Moon
gravity tidal effects. This effect is seen in comet core heating
as it passes near the sun. The core of the comet heats before
the surface does.

So if tidal heating is real, the moon certainly be said to
effect the Earth core heating. And core heating then could be
said possibly altering mantle state.

Star to star tidal heating would then be seen as a dark matter
effect. Begging the question of observing dark matter in this
solar system.