Japetus' surface composition (organic material?!?)

Caption NASA originale:"The polar water ice is relatively dark at this wavelength, so the ice cap is not seen. The next frame shows carbon dioxide on the surface. The carbon dioxide peaks at mid latitudes and shows less strength at the pole and along the equator (the dark band curving near the left edge of the image). The third frame shows the strength of water absorption on Japetus. The brightest regions are due to water ice near the pole. The grayer areas indicate water bound to minerals on the surface. The color composite shows water as blue, carbon dioxide as green, and non-ice minerals as red".