At https://phys.org/print447402256.html … we are told it takes 120 million years for a slab of anicent sea floor to subduct to a sufficient distance into the Mantle where it can cause the core to cool. This, in turn, causes the liquid iron in the Earth's outer core to flow more vigorously – to produce a reversal of the Earth's magnetic field (courtesy of the modelling methodology). What this really says is that scientists do not like the idea of the earth's magnetic field reversing – or the core rotating faster than the outer shell (or crust). This is classic modelling using a previous model – modelling on modelling.
Over at https://phys.org/print447400093.html … earth may have had a crust much earlier than currently assumed – in fact, millions of years earlier. Counting strontium atoms in rocks in northern Canada evidence would seem to show the crust formed hundreds of millions of years earlier. Crust is richer in minerals than younger volcanic rocks. Crust is also lighter and richer in silicon, for example. Once again, zircons were used – a mineral that keeps popping up in these research papers on the age of the earth and its rocks.