Adjust oven rack to middle position and heat oven to 450°F Toss carrots, parsnips, 1 teaspoons thyme, vinegar, marmalade, ginger, 1/2 teaspoons salt, 1/8 teaspoons pepper and melted butter in 13x9inch pyrex dish. Pour water over vegetables, cover with foil, and roast until vegetables just begin to soften, about 20 minutes.
Remove foil and continue to roast, tossing occasionally, until vegetables are tender and browned and liquid is reduced to thick glaze, 20-25 minutes. Add remaining teaspoons thyme and cubed butter and toss. Adjust seasonings and serve.