Well if i recall correctly all ley lines follow some form of magic. Ley lines come from places of power and spread out across the world so they are "tainted" to use your vernacular with that type of energy, earth magic, dark magic, fire, light, ectomanctic, divination, etc. Even in game terms i wouldn't just have a carte blanche leyline of pure power unless you ranked up it's refresh cost to at least that of soulfire. That being said my suggestion is to make it a ley line of Spirit and leave it at that.
As for compels, rememeber ley lines have no conscious aspect to compel you, it is all unconscious. A ley line of earth magic might make you slower to come to conclusions, more worried about testing the stability of your theories. You might become reluctant to go to high places or leave terra firma for any length of time. and you might start avoiding air magic as it is your elemental opposite.