Move oven rack to lowest position. Heat oven to 325°F. Spray roasting pan with cooking spray.
Remove and reserve fennel tops; coarsely chop bulb. In roasting pan, place fennel tops, chopped fennel, celery, carrots and 6 cloves of the garlic. Finely chop remaining 4 cloves garlic. In small bowl, mix chopped garlic, marmalade, honey, mustard, chile powder, tarragon, oregano, curry powder, salt and pepper. Cut half of orange into thin slices; cut other half into quarters.
Discard giblets and neck from turkey. Using fingers, gently loosen skin covering turkey breast and thighs; carefully spread marmalade mixture between skin and meat. Place orange slices between skin and meat. Place orange and onion quarters in turkey cavity. Fold wings across back of turkey so tips are touching.
Place turkey, breast side up, on vegetables in pan. Rub outside of turkey with oil. Sprinkle with salt and pepper, if desired. Tuck legs under band of skin at tail. Insert ovenproof meat thermometer so tip is in thickest part of inside thigh and does not touch bone. Do not add water to pan.
Roast uncovered 1 hour 30 minutes. Cut band of skin to allow inside of thighs to cook thoroughly. Place a tent of foil loosely over turkey. Roast 2 hours 30 minutes to 2 hours 45 minutes longer or until thermometer reads 165°F and legs move easily when lifted or twisted. (Skin will be dark golden brown.) Remove turkey from oven; let stand 15 minutes before carving. Cut celery and carrots into 2-inch pieces.