Board Thread:Questions and Answers/@comment-24439089-20140119020839/@comment-5398287-20140119024630

I don't think this is really enough evidence to support the Avatar concept.

Though Burn does sound like a fire-type Zanpakuto release command, remember that 3/4 of the known fire-type Zanpakuto have Shikai commands that have nothing to do with fire or flames (Snap, Tobiume; Crush Down, Tengumaru; Sever, Raika) so conversely, having a fire-related command doesn't make it fire-type. For all we know, it's just energy flowing off the blade.

Kaien is the only really solid example, but even then it wasn't really emphasized in the story.

Ganju uses fireworks in addition to his earth magic, and for all we know has learned/knows more types of magic than he displayed during the SS arc.

Finally, Kuukaku. Using one lightning-based Kido spell doesn't even come close to having a lightning theme about her. If she could generate electricity, maybe, but as pointed out above,character have frequently used Kido spells that have nothing to do or are the opposite of their usual powers.

In summation, not, there isn't really an elemental theme running through the Shiba clan because 1. lots of characters use attacks of different elements, and 2. none of the elements mentioned have been emphasized or made prolific enough to be considered a theme.