The Paletará Caldera: a lithofacies analysis of a supereruption in the Northern Andes, Colombia

The Paletará Caldera deposits represent the only well-defined geological and geomorphological evidence in Colombia of a large caldera-forming eruption. The deposits are composed mostly of ignimbrite, reach up to 300 m in thickness, crop out in an area of 2300 km, and yield an estimated bulk volume of 258–275 km 3 . Physical descriptions indicate lag breccias near the caldera rim, welded eutaxitic facies at the base of the deposit and non-welded facies at the top. Lithofacies variations suggest fluctuations in flow boundary zones during the progressive aggradation of a sustained pyroclastic density current. Further petrographic analyses revealed an ignimbrite deposit composed of pumice and lithic fragments embedded in a fine ash matrix of glass shards, plagioclase, quartz, and biotite. Devitrification textures, columnar jointing, lithophysae, spherulites, and welding ranks III–IV suggest high-temperature emplacement and slow cooling. The estimated volume of 258–275 km 3 corresponds to a VEI 7, demonstrating that the Paletará Caldera was formed by the most voluminous eruptive event documented so far in the geological history of the Colombian Andes. • Paletará Ignimbrite records the largest eruption in the Colombian Andes • Bulk volume of the Paletará Ignimbrite range between 258 to 275 km 3 • Paletará Caldera is the only well-defined supervolcano in Colombia • Similar eruptions would have regional to global impact