So everybody thinks Geo Force can kill the guy made of pure ice who can freeze the blood in his veins or flash freeze him solid or any other number of things Iceman can do.
That won't stop Iceman from freezing Geo Force's internal organs, or freezing his blood, or absorbing all the moisture from his body and leaving him a dried out husk. All this stuff can be done nearly instantaneously as well.
And so what his punch slightly shifted Earth off it's axis, he hits Iceman and he shatters, then reforms. As hard as it is to beat DC Elementals, Iceman is essentially the same thing.
Does GF even have internal organs or blood in Earth form? Then you have to consider GF's gravity manipulation powers and shields and his thermal/magma blasts and abilities.
Getting hit with lightning is not the same as having blood frozen in your veins or having your moisture drained. Iceman's a literal ice elemental and even if GF used his magma blasts, he could just reform or turn into mist, enter his body and reform from inside. He killed Fuego that way.
Uhm he, Ge0 Force, has thermal abilities too. Not to mention his gravity shields. How do you know Iceman's energy/cold abilities can penetrate GF's grav shields?
Iceman's abilities are thermal too. He doesn't make ice, he just sucks all the heat out of an area and ice forms as a result.
Also, a gravity force field won't stop Iceman from directly affecting GF. He doesn't need to shoot him or touch him, he just thinks about it.
Oh, and Iceman can be in multiple places at once. And transfer his consciousness to a new body he can make instantly.
And Fuego was a fire elemental. He burned hot enough to melt through several feet of solid rock in a few seconds, sucked Iceman's energy from him, and a few seconds later, Iceman froze him solid by reforming inside his body, which was made of fire.