@JTT,
Whenever we find really old rock belts, we can add to our understanding of how old land masses were emplaced, or the mineralogical makeup of the early crust (Most scientists have stated that the early crusts should be equally divided among continental, oceanic, and deep mantle materials.
The "fabric" of the old landmasses and their migration directions adds to our knowledge of mineral and resource belts (Thats what Im mostly interested in).
Rocks in Churchill must be older than 4.2 By because the dates were set by U/Th/Nd dates , so there were probably even older sequences of melting rock. We could be looking at a chemical "fossil" of the cooling earth up there in Canada.