After an uneventful landing, the pilot was cleared to taxi to the terminal. During the taxi, a ground marshaller signaled for the airplane to be turned (left) toward the northwest. The flight crew initiated a left turn. During the turn, the right wing tip of the airplane collided with a wing deicing cart. The cart tumbled and bounced back toward the trailing edge of the right wing. A portion of the cart impaled the right aileron, causing substantial damage. The captain and first officer did not see the deice cart in time to stop the right wing from striking it during the turn. Subsequent investigation revealed that the marshaller was using a spot on the ramp to park the accident airplane that was intended to be used for a smaller aircraft. Also, the ramp area at the airport did not have any lead-in lines or markings to provide taxi guidance, nor was a ‘safe movement’ zone designated. Additionally, the decing cart had been noted as a potential hazard by the previous station manager; however, it was not moved because of its needed proximity to an electrical source. Probable Cause: failure of the ground marshaller to marshal the airplane into a correct parking place on the ramp, her failure to verify clearance between the right wing of the airplane and the ground de-ice cart, and failure of the flight crew to ensure clearance of the right wing as the airplane was being taxied into the parking place. Factors relating to the accident include: a congested ramp facility, and inadequate ramp markings.