Is the husband's statement to his wife with whom he has not consummated the marriage: "If you leave without my permission, you are no longer under my marital authority," considered a divorce, and does that require a new marriage contract and a new dowry?

If the anger is so severe that one is unaware of what is being said, then nothing takes effect. If awareness is present, and the wife does not go to her father's house, then nothing results from that. However, if she leaves without permission, then an expiation for an oath is required. And the statement "You have left my عصمة (authority/bond of marriage)" is a veiled expression of divorce (kinayah talāq); if divorce was not intended by it, then nothing takes effect, and the wife remains within the عصمة.