The airline transport certificated pilot landed on runway 04, a snow-covered gravel runway, which required a correction for a left crosswind. The operator reported that after landing, as the pilot was turning the airplane to the left in order to back-taxi on runway 04, a gust of wind lifted the right wing, and the left wing and propeller struck the runway. The airplane sustained substantial damage to the left wing. The operator reported that there were no preaccident mechanical anomalies with the airplane.