Yes.
The Dark Ages began around 540AD and was likely caused by an impacting fragment from a comet.
Well, insofar as it's meaningful to argue about a historical term... Historians generally consider the Dark Ages to have begun in the fifth century, when a series of barbarian peoples invaded the Mediterranean world and destroyed urban civilization.
Come on, blam, you of all people know that a comet is merely a snowball and would not survive through our atmosphere.
I think the term would be "asteroid" rather than "comet".
Hudson Bay maybe?