Preheat the oven to 425 degrees F.

Season the snappers with the salt and pepper. Place the orange slices on the bottom of a large roasting pan in 2 columns of 4 orange slices. Place 3 sprigs of rosemary across the each of the 2 rows of oranges. Lay the fish on top of the orange slices, and divide the rosemary leaves, orange zest, garlic cloves, and olives evenly over the tops of the 2 fish. Pour the wine and orange juice around the fish, and drizzle each fish with 2 tablespoons of the olive oil. Place the fish in the oven and roast, uncovered, for 20 minutes. Remove from the oven and add 2 tablespoons of olive oil over each fish. Return to the oven and continue to cook until well caramelized, about 15 to 20 minutes. Remove the fish from the oven and drizzle with the remaining 1/4 cup of olive oil.

Serve immediately, with the pan drippings drizzled over the top of the fish.