I always assumed it was wind and lightning seeing as how Gaara's father had it and he was from Wind country where that affinity is more common, and that Gaara's ability was probably Jiton all along only permanently activated through his mother's will. Gaara's too has a wind affinity. The Edo from Kumo had Jiton as well and I'm assuming he had lighting release, this I came to the conclusion Jiton is made up out of wind and lightning.
Wind and earth or earth and lightning sound about right too though.