Sedimentación del mioceno superior plioceno en el flanco norandino de los Andes centrales venezolanos

Abstract

A sedimentary model of Betijoque Formation (Upper Miocene – Pliocene) is proposed from the outcrops of Betijoque - Sabana de Mendoza zone. This research was carried out through fluvial facies analysis taking into account facies associations, architectural elements and geometric relationships. The interpretation allows to define their sedimentology meaning and their palaeogeography position within the proposed model. In the present study Betijoque Formation was divided into three units: Unit I (base), which has been characterized by bars and channels with lateral accretion, mainly sands and sometimes gravels. This Unit is interpreted as a meandering river formed mostly by sand. Unit II (middle) whose most important feature is an upwards coarsening of grains in the channels and bars. Accordingly, it has been interpreted as a meandering gravel river. And finally Unit III, which is represented as the top of the sequence and has been defined as fluvial and amalgamated colluvial deposits, which are adjusted to a braided deep gravel river system. In conclusion, the vertical sequence of Betijoque Formation is interpreted as a prograding alluvial fan system and the three units are located in middle and distal parts of the model.