Boletín Geológico, 47, 35-65, 2020 https://doi.org/10.32685/0120-1425/ boletingeo.47.2020.494 Lithology and geochemistry of the Guadalupe Group base around Tunja, This work is distributed under the Creative Commons Attribution 4.0 License. Boyacá, Colombia Received: May 12, 2020 Revised: July 27, 2020 Accepted: September 17, 2020 Litología y geoquímica de la base del Grupo Guadalupe, en los Published online: December 28, 2020 alrededores de Tunja, Boyacá, Colombia German Martínez Aparicio1, Pedro Patarroyo2 and Roberto Terraza Melo1 1. Servicio Geológico Colombiano, (SGC), Bogotá, Colombia. 2. Universidad Nacional de Colombia, (UNAL), Bogotá, Colombia. Corresponding author: German Martínez Aparicio,
[email protected] Abstract The base of the Guadalupe Group, in the Tunja area of Colombia, contains cherts, porcellanites, mudstones, and siltstones with subordinate quartz arenites. The lithostratigraphic description of two stratigraphic sections showed that the dominant facies have fine granular textures and siliceous compositions, which considerably differ from those of the prevailing sandy terrigenous facies described in the type locality in the Eastern Hills of Bogotá, in the Arenisca Dura Formation, the basal unit of the Guadalupe Group in this sector. The units that form the Guadalupe Group (base of the Guadalupe Group, Plaeners, and Arenisca Tierna) markedly differ from each other morphologically, which facilitates their mapping because the base and top units generate a steep morphology, and the intermediate units form surface depressions or valleys, similar to the morphology of the Guadalupe Group in its type locality in the Eastern Hills of Bogotá. The base of the Guadalupe Group consists of cherts and porcellanites toward the NW of the study area (Alto del Gavilán section), with mudstones, siltstones, quartz arenites, and to a lesser extent porcellanites and cherts prevailing toward the SE (Vereda Salitre section).