PALEOENVIRONMENTAL RECONSTRUCTION OF THE OLIGOCENE- MIOCENE DEPOSITS OF SOUTHERN CARIBBEAN (CARMEN DE BOLIVAR, COLOMBIA) BASED ON BENTHIC FORAMINIFERA
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Resumen
The benthic foraminifera from an Oligocene-Middle Miocene stratigraphic section were used to interpret the deposi-tional environments of these sediments. The examined stratigraphic section (Carmen de Bolivar section) located on the arroyo Alferez (Colombia) is 1950 m long and mainly consists of shale and siltstone with sandstone layers belonging to the Carmen Formation, Oligocene-Middle Miocene in age.
Paleobathymetric and paleoenvironmental interpretation were based on the foraminiferal analysis of 80 samples col-lected every 10-15 meters along the entire length of the section.
This study shows the results of a quantitative analysis of the benthic foraminifera greater than 63µm. Several foraminiferal associations have been individuated within the section:
· Associations dominated by planktic foraminifera with variable percentages of benthic foraminifera either cal-careous or agglutinated. These associations are interpreted as belonging to marine environment from the upper bathyal zone.
· Association dominated or totally composed by agglutinated foraminifera. The calcareous foraminifera within this association are rare and poorly preserved. The agglutinated foraminifera are abundant, fnely to middle agglutinated and mainly small-sized (>63-125 µm). This association indicates a turbid water condition and suggests a organic-rich upper-middle bathyal depositional environment.
Keywords: Benthic foraminifera, Oligocene, Miocene, Colombia, paleoecology.
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Referencias
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