Paleoenvironment /Paleoecological study of the Miocene deposit from the Zemalat El Amir Abdelkader region (Chellala mountains, NW Algeria)

Abstract

In the vicinity of Zemalat El Amir Abdelkader, south of the Chellala Mountains, a final marine incursion reached the northern margins of this region — namely, the Miocene transgression. In this locality, the Lower Miocene lies horizontally and transgressively over older Cretaceous terrains. It corresponds to deposits of two distinct lithological units. The lower unit is characterized by marl rich in Ostrea, while the upper carbonate unit is rich in pectinids. Mineralogical analysis of several limestone samples from the upper unit shows that this facies is dominated by calcite (97%) with a lesser amount of quartz, estimated at around 3%. The sedimentological analysis, based on lithofacies and biofacies inventory, revealed three main facies. Based on their facies characteristics, a shallow marine to littoral–intertidal environment was proposed for the studied sequence.