What is the salt plume on Enceladus?

It's an ice geyser, kind of like Old Faithful in Yellowstone is, bu the fuel for the ice geyser is gravitational flexing caused by gravitational resonance with Saturn and other Saturn moons, instead of being located over mantle plume like ( a hot-spot) like Yellowstone and Hawaii are, although there may be a similar mechanism contributing to the geyser activity on Enceladus as well. Enceladus is like Europa in many ways - a second satellite that may have a salt water ocean underneath the exterior ice surface.