Why would the rate of sea-floor spreading increase?

Question

I have evidence that the rate of sea-floor spreading almost doubled around 4-5 million years ago. It rose from around 13.3 mm per year to over 30 mm per year. only problem is, I cannot think of anything which could have caused this. any ideas?

Please help.

Answer 1

Seafloor spreading is never uniform.  It varies widely, depending not only on time but also on place.

One article:  Breaking New Ground on the Ocean Floor

http://www.newscientist.com/article/mg14...