[omnivore]

"...could great chunks of ice have been blown all over the place causing gouges..."

I wouldn't say no so quickly. Larger meteors (~ 10's of meters and up) have a large enough mass-to-surface-area ratio that the heat from entry does not get very far in. (Most of the heat is produced by ram effect (Charles' law) rather than friction.) The pressure that builds up on the side facing in the direction of travel usually breaks apart large meteors, which are often not stuck together that solidly to begin with. The superheated gas will of course penetrate any cracks or interstitial gaps between chunks, which helps the breakup. But, the interiors of the chunks can still be quite cold at impact. If some of the chunks of a large meteor were ice, they could still be mostly frozen up until impact.

This may have been the situation with Tunguska, which featured a large energy release but little rocky or metallic debris was ever found, and no significant crater. So it may have been mostly ice, and broke up just before impact.

[gleeaikin]

By great chunks of ice, I meant chunks that might have been blown out of any crater blown into the ice sheets. Like water dropping into a puddle splashes out water from the puddle.