Curious; what would cause such a spike? {Wasn't there a super nova in our region of the cosmos about that time?} How does such a spike effect carbon-14 dating in general, and around the world?
http://www.freerepublic.com/tag/charlemagneevent/index
http://www.freerepublic.com/tag/fusamiyake/index
http://www.freerepublic.com/tag/iron60/index