The Pliocene Paletará Caldera: the largest known eruption at the Northernmost Andes in Colombia
Juan Alvarez-Silva1 , Susana Osorio-Ocampo2,3, Hugo Murcia3, María Luisa Monsalve-Bustamante2
Affiliations: 1Instituto de Geología, Universidad Nacional Autónoma de México, México; 2Servicio Geológico Colombiano, Manizales, Colombia; 3Departamento de Geología, Universidad de Caldas, Manizales, Colombia.
Presentation type: Poster
Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall
Poster Board Number: 164
Programme No: 3.5.23
Abstract
Plio-Pleistocene ignimbrite deposits located at 2° N in Colombia, are evidence of a significant output of magma associated with a caldera-forming eruption in the northernmost Andean volcanic arc. These deposits are formed by a poor-sorted mixture of crystals, pumice and lithic fragments with a minimum calculated volume of 200 km3. Based on detailed field-collected data and microscopic descriptions, a lithofacial analysis is presented as the basis of the origin and sedimentation processes associated with the deposits. The ignimbrites exhibit no evidence of long-lasting sedimentation gaps, reaching thicknesses of 230 m and covering an area of ~2000 km2. They display a relatively uniform lithofacial distribution dominated by either welded or non-welded massive lapilli-tuff. Lihofacial variations are given by crystals, pumice, and lithic content changes. Welded lithofacies display columnar jointing and fiamme structures. Based on the results, it is proposed that the Plio-Pleistocene ignimbrites were formed by a sustained, quasi-stable, and non-homogeneous pumice flow within a fluid-scape dominated flow-boundary zone. They were deposited radially following the caldera collapse eruption and formed the Paletará Caldera 2.6 My ago. The ignimbrite deposits are formally defined as the Guacacallo and Popayán Formations and together are the evidence of the largest Pliocene eruption recorded in the Colombian volcanic arc.