The caldera is the source of the Los Colorados ignimbrite, which was erupted 7.9-7.76 million years ago. This ignimbrite is formed by highly welded dacite, is rich in pumice and has a dark pink colour. Quartz, sherds are also widespread. This ignimbrite covers a surface area of , spilling into Argentina. Part of the Los Colorados ignimbrite has been identified at the Laguna Amarga caldera.