re:And they go on to say...
A final answer to the question could be many years away, though. Clues from meteorites alone don't seem to be settling the debate. "If anything, I think the problem may be getting worse instead of better," Mittlefehldt said.
"We're only going to sort that out by getting sample returns from Mars," he said. On this point, Nishiizumi, Borg and the others agree. The need to send a spacecraft to the planet to bring back fresh samples from known locations is one proposal about which there is no debate.
http://www.space.com/scienceastronomy/solarsystem/martian_meteorite_000830.html