New zircon U–Pb ages and their problems in the integration of the Geological Map of Colombia

Abstract

The Geological Map of Colombia is periodically updated by the Colombian Geological Survey to incorporate advances in geological mapping, geochronology, and tectonic interpretations. The 2023 edition integrates geological information published up to March 2022 and includes a comprehensive reassessment of isotopic ages, particularly zircon U–Pb data, within a chronostratigraphic framework. This contribution examines the impact of new geochronological constraints on the interpretation and compilation of the Geological Map of Colombia and discusses major cartographic challenges identified during its preparation. Five representative case studies are analysed: the Cajamarca Complex, the Tierradentro Gneisses and Amphibolites, the Quebradagrande Complex, high–pressure metamorphic rocks of the Central Cordillera, and Jurassic metamorphic rocks in the Sierra Nevada de Santa Marta. These examples illustrate how inadequate geological mapping, inconsistencies in lithostratigraphic definitions, and interpretations based solely on geochronological data can lead to erroneous chronostratigraphic assignments and misleading tectonic reconstructions. The study highlights the importance of integrating field observations, lithostratigraphic relationships, structural geology, and geochronology in regional geological compilations. The reassessment of nearly 2000 isotopic ages published between 2014 and 2022 led to significant updates in the Geological Map of Colombia 2023. These include the recognition of a Permian magmatic arc along the eastern flank of the Central Cordillera and Upper Magdalena Valley, the extension of the Carboniferous plutonic record in Colombia, identification of Ordovician volcanic rocks in the Santander Massif, revision of the age and extent of the Quebradagrande Complex, and refinement of the temporal and tectonic significance of high–pressure metamorphic belts. New U–Pb ages also enabled the subdivision, redefinition, and reassignment of several chronostratigraphic units previously grouped under broader geological categories. These revisions provide new insights into the tectonic and magmatic evolution of the northwestern margin of South America and demonstrate the critical role of combining geochronological information with detailed geological mapping in regional geological syntheses.