looking at those images alone it definitely looks like, if UG mining is a go, then just use base case pit to scoop out the dome, then UG for all of those extensions.
I do understand for the PFS including the expansion pit to add in those great hits we had down there, but economical mining wise your suggestion looks the best plan.
All based on the limited information available of course.
Another factor that I doubt can be priced in now or bareky speculated on, but once the open pit is well into years of mining, i'm sure there is more flexibility for drill testing extensions to veins and the NFP contact under T3.
Costly from surface right now, and probably won't even be a MOD mine by that stage, but UG extensions I would guess are likely to extwnd mine life WAY down the track.
Anyway, back to your point, I would also guess T3 underground scoping, and T3 open pit DFS will be nearing completion around the same time, plus A4 could have a JORC by then as well, so T3 feels like it still has some evolving to do. A complex DFS if these scenarios all have to be addressed to some extent.
