Eocene to Miocene palynology of the Amagá Basin comparada con la Región Caribe

• Published in: Revista de la Academia colombiana de ciencias exactas, físicas y naturales Vol. 47; no. 185; p. 925
• Main Authors: Pardo-Trujillo, Andrés, Plata-Torres, Angelo, Ramírez, Edwin, Vallejo-Hincapié, Felipe, Trejos-Tamayo, Raúl
• Format: Journal Article
• Language: Spanish
• Published: Academia Colombiana de Ciencias Exactas, Fisicas y Naturales 01-10-2023
• Subjects: Analysis; Evolution; Facies (Geology); Geomorphology; Microfossils; Relative dating (Chronology); Sedimentary basins
• ISSN: 0370-3908
• DOI: 10.18257/raccefyn.1921

The Cenozoic sedimentary basins of northwestern Colombia contain clues to understanding the evolution of past ecosystems and their possible relationship to regional events, such as the uplift of the northern Andes and the collision of the Panama-Chocó Block with the South American continent. However, these basins have not been thoroughly investigated. This work aims to fill this knowledge gap by performing a comprehensive palynological analysis of the Amagá Basin (Valle del Cauca). Three outcrops were studied to determine their depositional ages, paleoenvironments, and overall floral composition over time. To contextualize our analyses, a comparison was made with two drill holes (ANH-SSJ-Nueva Esperanza-1X and ANH-San Jacinto-1) in the Sinú-San Jacinto Basin in the Colombian Caribbean. The application of the palynological zonation from the Llanos Basin in eastern Colombia was also used to evaluate its suitability in the Amagá Basin. The age of deposition was determined by using several traditional palynostratigraphic markers, including Perisyncolporites pokornyi, Foveotriporites hammeni, Retibrevitricolporites speciosus, Magnastriatites grandiosus, Concavissimisporites fossulatus, Clavainaperturites microclavatus, and Polypodiaceoisporites pseudopsilatus. This assemblage indicates a Middle to Late Eocene, Oligocene, and Miocene age spanning from ~40 to 18 Ma (~22 Myr). However, there are also some differences with respect to the Llanos zonation, such as the absence of Cicatricosisporites dorogensis. Based on this age model, we question whether it is correct to include all these deposits in a single lithostratigraphic unit under the rank of a formation.