Re: Fractures... except that the Inca City formation
consists of ridges, forming more or less rectilinear enclosures. Thus analogous to Chan Chan in the Peruvian desert (not really "Inca" at all, but close enough. The analogy is even closer to Casas Grande in Northern Mexico, in my estimation... but I digress.)
Have yet to see any fractures like this created by impact. That's not to say it couldn't happen, though.
The perimeter ridge forming the upper portion of the circle is pretty neat. Maintains a pretty uniform narrow width for many kilometers. Wonder why it wasn't noticed before -- all those dozens of pictures!
Still, it's a very interesting surface feature, this "Inca City."
Cheers, B R Felix