INFLUENCIA MARINA EN EL EOCENO TARDÍO DEL ORIENTE Y SURORIENTE DE COLOMBIA
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Authors
Santos, C.
Jaramillo, C.
Torres, V.
Rueda, M
Flórez, P
Rodríguez, G
Advisors
Evaluators
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Universidad Industrial de Santander
Abstract
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Durante el Eoceno Tardío en las Cuencas Subandinas de Colombia tuvo lugar la depositación de uno de los más importantes reservorios del país: la Formación Mirador. Diversos modelos deposicionales reconocen un ambiente típicamente fluvial para su base, y ambientes más transicionales para su tope. Sin embargo, la presencia de una influencia marina en el tope del Mirador es aún discutida, y la distribución geográfica de este probable evento es desconocida. Con el objeto de establecer la paleogeografía de esta ingresión marina se analizaron palinológicamente 77 pozos y 3 secciones ubicados en el Oriente de Colombia. La influencia marina en los sedimentos se estableció determinando la Paleosalinidad asociada mediante un Índice de Salinidad (SI), que describe la relación entre palinomorfos marinos y continentales. La ingresión marina está registrada en dos áreas: la primera, en la Cordillera Oriental y el Piedemonte Llanero Central; y la segunda, en la cuenca del Putumayo. El comportamiento de la paleosalinidad sugiere que al Sur, en la Cuenca del Putumayo, la ingresión marina invadió el territorio Colombiano en sentido S-N a través de la costa Ecuatoriana. Sin embargo, cómo ingresó a la Cordillera Oriental y al sector central del Piedemonte no es claro, y los modelos paleogeográficos propuestos no lo explican satisfactoriamente. Un nuevo modelo paleogeográfico para el Eoceno Tardío deberá ser planteado.
Palabras Claves: Eoceno Tardío; Palinología; Índice de Salinidad; Influencia Marina; Formación Mirador
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
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