Preheat oven to 350°. In a medium bowl, mix together the crushed gingersnap cookies, pecans and butter. Press into the bottom and about an inch up the sides of a 9-inch springform pan. Bake crust 10 minutes in the preheated oven. Set aside to cool. In a medium bowl, mix together the cream cheese, 1/2 cup sugar and vanilla until smooth. Mix in eggs, one at a time, blending after each. Set aside 1 cup of the mixture. Blend 1/4 cup sugar, pumpkin, cinnamon and nutmeg into the remaining mixture. Spread the pumpkin-flavored batter into the crust and drop the plain batter by spoonfuls onto the top. Swirl with knife to create a marbled effect. Bake 55 minutes in the preheated oven, or until filling is set. Run a knife around the edge of the pan. Allow to cool before removing pan rim. Chill at least 4 hours before serving.