Can spouse legally close a joint checking account prior to filing for divorce ?

If it is a joint checking account, then it would likely be marital property, which is subject to division in the divorce. She will have to account for that money in the divorce proceedings. Once divorce proceedings have been commenced, most jurisdictions have standing orders prohibiting anyone from changing or closing accounts. You should consult with an attorney in your area immediately to discuss your options, including whether you have grounds to pursue divorce so that you can protect your property.

While her actions were not criminal or court-prohibited, it is likely that the Court will take into account her actions as part of its judgment.

You probably gathered this from the previous responses, but I'll risk gilding the lily for clarity's sake: If you're worried about your spouse running off with your stuff, go ahead and file for divorce or legal separation. Even if you don't go through with the divorce, it should make her think twice.