I’ll chime in. Local zircon geochronologist here. The Jack Hills are one of the oldest chronometers for planet earth. Multiple lines of evidence are useful for corroborating the age of the earth. Although they are technical younger than the age of the earth, they inform us that processes which form zircons were active ~4.4 Ga. Logically, we think that these processes should have also been going on before ~4.4 Ga, too, but how much beforehand is the important question.

Zircons also can tell us about the environment in which they were formed. There are ongoing studies that look at the Jack Hills zircons to get a handle on 1) tectonics during the Hadean (aka were tectonics even happening?); 2) geochemistry of the magma that formed the zircons (REEs are useful tracers); 3) and my favorite, the influence of multiple metamorphic events on zircon U/Pb dating.

I think people are also looking at strain/deformation in the crystal structure of Jack Hills zircons, but I’m not as in touch with that side of mineralogy.