In small bowl, combine olive oil, gingerroot and garlic; mix well. Place chicken in large shallow dish. Brush garlic mixture over chicken, coating all sides. Sprinkle chicken with salt and pepper. Let stand at room temperature for 15 minutes to marinate.
Meanwhile, heat grill. In small bowl, combine marmalade, orange juice and sesame oil; mix well. When ready to grill, place chicken on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 25 to 30 minutes or until chicken is fork-tender and juices run clear, turning and brushing frequently with marmalade mixture during last 15 minutes of cooking time.
Place orange slices on grill during last 5 to 8 minutes of cooking time; turn once. Serve chicken over orange slices.