Micropaleontology and stratigraphy of the Arroyo Saco section, Atlántico Dept.
DOI:
https://doi.org/10.32685/0120-1425/bolgeol3.1.1955.456Keywords:
Sedimentation cycle, fauna, foraminifera, Miocene, mollusks, Caribbean province
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Copyright (c) 2019 Servicio Geológico Colombiano
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Abstract
The present report deals with the lithology, micropaleontology, and stratigraphy of the 1730 m thick section exposed in the Arroyo Saco in the Dept. of Atlántico, about 37 km SW of Barranquilla.
The exposed layers belong to the Miocene, from the basal to the lower part of the Middle Miocene and are inclined to the East with a dip of 10-15º.
In this series, several major sedimentation cycles can be recognized. Each one starts with pelagic clays with foraminifera that pass upwards to sandy clays and finally to coastal sands and sandstones, partly calcareous without foraminifera but rich in mollusk s. Thus, foraminifera are almost restricted to the lower part and mollusk s to the upper part of each cycle.
The largest cycles correspond to the 3) Middle Miocene red (= ? Helvetian), 2) Lower Miocene high (= ? Burdigalian), 1) Lower Miocene low (= ? Aquitanian).
Cycles 2 and 3 are subdivided into subunits.
The mollusks collected in Arroyo Saco are described in M. Barrios Monroy 1955. The systematic part of the present report deals with the foraminifera of this section, most of which are figured on five plates. The microfossils are typical members of the fauna of the Caribbean province.
