Hematite on Mars is generally thought to have formed either in pools of water or from volcanic activity.
A comment to the answer to the question: How do hematite and magnetite form? states that sodium hypochlorite can act as an oxidizer to help form hematite.
I know hypochlorite is different from perchlorate, but Mars contains so much perchlorate that its soils are considered to be toxic to life.
Could the perchlorates on Mars have been influential in the formation of hematite?