NANOFÓSILES CALCÁREOS DE LA SECCIÓN ARROYO ALFÉREZ (CARMEN DE BOLÍVAR): UNA BIOZONIFICACIÓN PRELIMINAR PARA EL OLIGOCENO – MIOCENO MEDIO DEL NORTE DE COLOMBIA
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Universidad Industrial de Santander
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Un primer esquema biocronológico basado en nanofósiles calcáreos del norte de Colombia, se presenta como resultado del análisis de 40 muestras de superfcie de la sección Arroyo Alférez (Bolívar, Colombia). La nanofora está representada por Cyclicargolithus foridanus, Cyclicargolithus abisectus, Reticulofenestra minuta, Reticulofenestra minutula, Reticulofenestra media y Reticulofenestra pseudoumbilicus, con algunos niveles de Helicosphaera. Discoastéridos son importantes hacia el fnal de la secuencia. Se reconocen las biozonas NP23 a NN5, según el esquema de Martini (1971) y CP18 a CN4 según el esquema de Bukry (1973, 1975). Esto indica que el intervalo analizado va desde el Oligoceno Temprano (Rupeliense) hasta el Mioceno Medio (Langhiense-Serravalliense).
La biozonifcación de la sección del Arroyo Alférez, constituye el punto de partida para obtener un marco biocronológico del Cenozoico con base en nanofósiles para el norte de Colombia, con aplicación directa en la exploración de hidrocarburos, especialmente en áreas costa afuera.
Palabras clave: Nanofósiles, bioestratigrafía, Carmen de Bolívar, Oligoceno, Mioceno
A nanofossils-based biostratigraphic scheme is presented for the northern Colombia. Fourty (40) outcrop samples from the Arroyo Alférez section were analysed for nanofossils content. Taxa presented along the section are Cyclicargolithus foridanus, Cyclicargolithus abisectus, Reticulofenestra minuta, Reticulofenestra minutula, Reticulofenestra media and Reticulofenestra pseudoumbilicus. Helicosphaera sp. was abundant in some intervals, while Discoasterids increase to the top of the section. Biozones NP23 to NN5 (Martini, 1971) and CP18 to CN4 (Bukry, 1973; 1975) have been identifed, indicating Early Oligocene (Rupelian) to Middle Miocene (Langhian-Serravallian) age for the section. The biozonation of the Arroyo Alférez constitutes the frst nanoplanckton-based approach to construct a biochronologic scheme for the Cenozoic of northern Colombia with application on oil exploration of the offshore areas of the Colombian Caribbean basin. Key words: Nanofossils, bioestratigraphy, Carmen de Bolívar, Oligocene, Miocene.
A nanofossils-based biostratigraphic scheme is presented for the northern Colombia. Fourty (40) outcrop samples from the Arroyo Alférez section were analysed for nanofossils content. Taxa presented along the section are Cyclicargolithus foridanus, Cyclicargolithus abisectus, Reticulofenestra minuta, Reticulofenestra minutula, Reticulofenestra media and Reticulofenestra pseudoumbilicus. Helicosphaera sp. was abundant in some intervals, while Discoasterids increase to the top of the section. Biozones NP23 to NN5 (Martini, 1971) and CP18 to CN4 (Bukry, 1973; 1975) have been identifed, indicating Early Oligocene (Rupelian) to Middle Miocene (Langhian-Serravallian) age for the section. The biozonation of the Arroyo Alférez constitutes the frst nanoplanckton-based approach to construct a biochronologic scheme for the Cenozoic of northern Colombia with application on oil exploration of the offshore areas of the Colombian Caribbean basin. Key words: Nanofossils, bioestratigraphy, Carmen de Bolívar, Oligocene, Miocene.