What were said elements?

or to have an analogy - the convecting mantle is an inverted pendulum, and the plate pushes it one way or the other.

If yes, my immediate reaction is to think that the convecting mantle is essentially an unstable system (like... it obviously is not in a fixed steady state 😅, since it's convecting) - but that any slight push from the plate itself sets up the convection cell, rather than the other way around. Crazy?

So to come back to force balances and vaguely summarise what you've been saying: a plate with a large entrained mantle layer and one without (e.g., fig 10 from the last paper you linked) basically can have any particular plate velocity? There no strong correlation?

Interesting!

Forgive me, I'm having to skim the papers a bit (and I've been out of the game a few years :'( )

In dx.doi.org/10.1029/2018..., they don't talk too much about coupling to the convecting mantle - beyond the slab interacting with the lower mantle - but that kinda is convection, so I suppose it's a bit definitional..

But yeah, from my own lithospheric scale stuff, using non-newtonian rheologies and much higher resolutions was fairly important, so I'm naturally curious about the impacts it would have - though Becker does briefly touch on it.

From reading the Becker paper, it seems they show that some coupling is required, in that if the asthenosphere is too weak, results deviate from reality.
This does answer my 'which models' Q - e.g., all the EarthByte models have plate velocities imposed, etc. - so a fully dynamic model is neat.

Sorry, to give some context - I used to do a lot of numerical modelling, but it was lithospheric scale rifting, rather than full mantle subduction.

By coupled, I don't mean discontinuous, more that mantle convection does or doesn't impart 1st order effects on the lithosphere.

Yeah, that's kinda what I was getting at. If there is no clear correlation, to me it sounds like slab pull (and maybe ridge push or other gravitational body forces) would be the dominant forces, with coupling being 2nd order.
Which numerical models do you mean?

Could this be explained by limiting the slab pull force? If there is some upper limit on the slab pull (eg, mantle too viscous to accommodate more slab), it may explain why the lithosphere/mantle coupling is not necessarily indicative?

Could you give a brief glimpse of your ideas? (I can't access the springer chapter :( )