For the sake of analogy, let's take the Chixclub impactor and move it a mountain range akin to the modern Himalayas. Obviously we're dealing with an extinction level event here so I'm not concerned with the effects on life, and only loosely interested in the atmospheric effects. My primary concern is with the effects of the impact on the surrounding geology.
I'm mostly looking for information on how the area would look a few thousand years out - would the nature of the area better preserve a crater? Or would the ejecta fill the hollow and leave a sort of semi-flat (but still high altitude) plateau?
Feel free to ignore this, as I don't want to overburden the question, but does the result change if the impactor is at a lower speed (e.g. an orbiting body forced to deorbit)?
edit: per the clarification request below, here is a link to a spot on Earth most analogous to the environment I am imagining. A fairly wide stretch of a range of high peaks of marble and schist (et al) fairly well removed from an ocean. The impact's 'epicenter' would be surrounded by mountains on all sides.
Well, pre-impact. 'After the impact' is part of the answer I'm seeking.