Silent treatment hurts because there is no possibility of resolution as you have pointed out.

She might be hurt and in a LDR there isn’t a lot of ways to get to the bottom of things and if you have tried talking before and is hasn’t worked she is likely frustrated and is taking out her frustrations in this way.
I am in a LDR too and sometimes if I am not getting what I need I want to create space too.

However, I know I could not do this with my guy because it is a cold and manipulative way of handling it.
It is too painful for the other person.
She is either trying to punish you or she is in deep pain and this is her way of crying out.

Do you two have great communication? Are you sure you have heard what she is saying to you?
Is she trying to get you to THINK about what is going on?

Either way, I would tell her this is unacceptable. You might even mention that you will give her space after you find out that she is ok.
Silent treatment is a passive aggressive behavior and is not healthy.