[fhars]

No, the coal beds are far older and far thicker than the bit of end-cretaceaous soot that paper is talking about. The K-Pg boundary sediments are thin: http://en.wikipedia.org/wiki/File:Cretaceous_Paleogene_clay_...

Your typical coal bed is quite a bit thicker: http://en.wikipedia.org/wiki/File:Coal_mine_Wyoming.jpg