Cenozoic marine carbonate systems of Colombia
This paper is the result of the collaboration between our group at MMU and researchers at Stanford University and INVEMAR. Here Ecological Genetics lab member Dr Lina Barrios and colleagues describe the recent history of the Colombian Caribbean marine environments and the appearance of coral reefs in the area between the Oligocene (34 to 23 million years ago) and the Miocene (23 to 5 million years ago), before the appearance of the Isthmus of Panama. The chapter includes some comparisons between the geological periods and current coral reefs.
Silva–Tamayo, J.C., Rincón–Martínez, D., Barrios, L.M., Torres–Lasso, J.C., Osorio–Arango, C. (2020). Cenozoic marine carbonate systems of Colombia. 40p. Annex. In: Gómez, J. & Mateus–Zabala, D. (editors), The Geology of Colombia, https://doi.org/10.32685/pub.esp.37.2019.09
In this chapter, we report existing and new lithostratigraphic information and Sr–isotope chemostratigraphic ages of several Cenozoic marine carbonate successions deposited within numerous Colombian basins. This information is used to link main changes in the shallow marine carbonate factory to regional environmental/tectonic events in the tropical SE Circum–Caribbean. Our results and the available literature show that during the Eocene – early Oligocene transition, carbonate successions developed along the Alta Guajira (Macarao Formation) and the San Jacinto (Toluviejo and Arroyo de Piedra Formations) Basins, northern Colombia. These successions, which deposited along rimmed carbonate banks, mostly display heterozoan biotic associations, dominated by red algae and large benthic foraminifera. The development of this carbonate factory occurred during an interval of hothouse conditions through which mesotrophic and oligophotic marine conditions predominated. During the late Oligocene, carbonate sedimentation occurred along the Alta Guajira Basin (Siamana Formation), Lower Magdalena Valley Basin (Cicuco Limestones of the Ciénaga de Oro Formation), and Western Cordillera of Colombia (Vijes Formation). Predominant mesotrophic conditions resulted in the coexistence of mixed photozoan–heterozoan biotic associations and the development of patchy coral reefs along the predominantly siliciclastic continental shelves. During the early Miocene, carbonate deposition was absent in most of the Colombian sedimentary basins and was restricted to the Alta Guajira Basin, where photozoan biotic associations dominated the emerging rimmed coral–dominated carbonate platforms attached to the continental shelves. The change in coral reef architecture along the Alta Guajira Basin coincides with the onset of a global climate optimum and of local marine oligotrophic and euphotic conditions. The replacement of photozoan by heterozoan biotic associations in the Alta Guajira Basin during the middle Miocene likely resulted from the return to mesotrophic/oligophotic conditions due to the enhancement of the sediment supply to the Caribbean as the docking of the Panamá Block to northern South America reached its acme. The enhanced sediment supply to the Caribbean decreased the occurrence of well–developed reefs along the Caribbean region of Colombia (continental) during the late Miocene and Pliocene. This decrease, which parallels global trends, is only interrupted by the deposition of the late Miocene San Andrés and Pleistocene San Luis Formations (Los Cayos Basin), where photozoan biotic associations prevailed, and the Pleistocene La Popa Formation (San Jacinto Basin), which displays mixed photozoan–heterozoan biotic associations.