CRISM: Carbonate minerals in Nili Fossae

This image shows a site near Nili Fossae, a group of long, narrow tectonic depressions called graben, and reveals the presence of hydrated iron-magnesium (green) phyllosilicate and carbonate minerals (shown in yellow). Phyllosilicates, which include clay and clay-like minerals, form from the chemical reaction of water with igneous rocks. Carbonates form where carbon dioxide combines with the rocks. Minerals that formed by the chemical interaction of water or carbon dioxide with igneous rocks record…. [More at link]