Hi, all4me-

Yes, you are absolutely correct on the area... so the question boils down to: was this an M-class asteroid (http://en.wikipedia.org/wiki/M-type_asteroid), i.e. mostly nickel-iron, or did its impact just punch a hole in the crust and allow magma to escape, or did its impact and heat cause existing nickel-bearing rock to melt and concentrate said nickel, or something else entirely?

If the metal came from the asteroid, then we need to add in the dimension of the volume of the asteroid. Approximating it as a sphere and assuming that it hit obliquely (and had the same composition as the Sudbury asteroid), with its diameter being 42 miles(!!) (versus 16 miles for Sudbury), then the volume is 4/3*pi*r**3

Sudbury: 2144 cubic miles

RoF: 38,773 cubic miles ... 18x larger

My guess is that we're actually seeing a circumference-based deposit (either melting and concentrating existing nickel-bearing rock, or allowing magma to flow from the hole punched in the crust of the earth), which would be less spectacular... pi*diameter for a circle, and much more complex a formula for an ellipse (http://en.wikipedia.org/wiki/Ellipse). We don't know, but with all the staking around the edges of the RoF, it appears to be the working model being used by the geologists for pretty much all the companies exploring there. If you do that math, it's more like 3x. (the relative circumference of a circle is 2.625x, and ellipse is a bit bigger).