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Abstract
During Late Eocene in the Colombian Subandean basins one of the most important oil bearing Rocks in Colombia was deposited: The Mirador Formation. Most of the depositional models proposed recognize a typically fluvial environment for the Mirador´s base and transitional environments for its top. These models disagree about a probable Marine Influence in the Mirador´s Top, and the geographical distribution of this event remains unknown. In order to determine the paleogeography of this event, 77 wells and 3 sections were palynologically analyzed. The presence of the marine influence in the sediments was determined using a Salinity Index (SI) which describes the reverse relationship between continental and marine palynomorphs. Marine Influence was recognized in two areas: the first one, in the Eastern Cordillera and the Central-Eastern Foothills; and the second one, in the Putumayo Basin. Paleosalinity patterns suggest that in the Putumayo Basin the marine ingression flooded in to the Colombian territory in a South-North direction, through the Ecuatorian Coast. How the Marine Ingression flooded into the Eastern Cordillera and Central-Eastern Foothills is not clear, and paleogeographical models proposed can not explain it. A new paleogeographical model for the Colombian Late Eocene considering this event must be proposed.
Key Words: Late Eocene; Palynology; Salinity Index; Marine Influence; Mirador Formation
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References
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